[MRG+1] Fix: Replace pylab with matplotlib.pyplot #6754 (#6762)

* Fix: Replace pylab with matplotlib.pyplot #6754

 - one instance of 22 occurrences of pylab replaced with matplotlib.pyplot
 - bench_glm.py now free of pylab references
 - code executes properly

* Fix: Replace pylab with matplotlib.pyplot #6754

- one instance of 21 remaining occurrences of pylab replaced with
    matplotlib.pyplot
- bench_glmnet.py now free of pylab references
- code does not execute for extraneous reason: ImportError: No module named
    glmnet.elastic_net

* Fix: Replace pylab with matplotlib.pyplot #6754

- one instance of 19 occurrences of pylab replaced with matplotlib.pyplot
- bench_lasso.py now free of pylab references
- code executes properly

* Fix: Replace pylab with matplotlib.pyplot #6754

- one instance of 18 occurrences of pylab replaced with matplotlib.pyplot
- bench_plot_neighbors.py now free of pylab references
- code executes properly

* Fix: Replace pylab with matplotlib.pyplot #6754

- one instance of 17 occurrences of pylab replaced with matplotlib.pyplot
- bench_plot_omp_lars.py now free of pylab references
- code does not execute for extraneous reasons:
    - File "bench_plot_omp_lars.py", line 111, in <module>
    - ax = fig.add_subplot(1, 2, i)
    - ValueError: num must be 1 <= num <= 2, not 0
    - line 111 should probably be ax = fig.add_subplot(1, 2, i+1)

* Fix: Replace pylab with matplotlib.pyplot #6754

- bench_plot_parallel_pairwise.py now free of pylab references
- code executes properly

* Fix: Replace pylab with matplotlib.pyplot #6754

- bench_plot_ward.py now free of pylab references
- code executes properly

* Fix: Replace pylab with matplotlib.pyplot #6754

- bench_sgd_regression.py now free of pylab references
- code executes properly

* Fix: Replace pylab with matplotlib.pyplot #6754

- bench_tree.py now free of pylab references
- code executes properly

* refactor: Replace pl with plt

- replace instances of pl (as on import pylab as pl)
  with plt (as in import matplotlib.pyplot as plt)
- bench_glm.py clean

* refactor: Replace pl with plt

- replace instances of pl (as on import pylab as pl)
  with plt (as in import matplotlib.pyplot as plt)
- bench_glm.py clean of pl
- code does not execute for extraneous reasons

* refactor: Replace pl with plt

- replace instances of pl (as on import pylab as pl)
  with plt (as in import matplotlib.pyplot as plt)
- bench_lasso.py clean of pl
- code executes properly

* refactor: Replace pl with plt

- replace instances of pl (as on import pylab as pl)
  with plt (as in import matplotlib.pyplot as plt)
- bench_plot_neighbors.py clean of pl
- code executes properly

* refactor: Replace pl with plt

- replace instances of pl (as on import pylab as pl)
  with plt (as in import matplotlib.pyplot as plt)
- bench_plot_omp_lars.py clean of pl
- code does not execute for extraneous reasons

* fix: Fix bug that prevented graphs from displaying

* refactor: Replace pl with plt

- replace instances of pl (as on import pylab as pl)
  with plt (as in import matplotlib.pyplot as plt)
- bench_plot_parallel_pairwise.py clean of pl
- code executes properly

* refactor: Replace pl with plt

- replace instances of pl (as on import pylab as pl)
  with plt (as in import matplotlib.pyplot as plt)
- bench_plot_ward.py clean of pl
- code executes properly

* refactor: Replace pl with plt

- replace instances of pl (as on import pylab as pl)
  with plt (as in import matplotlib.pyplot as plt)
- bench_sgd_regression.py clean of pl
- code executes properly

* refactor: Replace pl with plt

- replace instances of pl (as on import pylab as pl)
  with plt (as in import matplotlib.pyplot as plt)
- bench_tree.py clean of pl
- code executes properly

* docs: removed pylab references from comments

* docs: removed all pylab references

- replaced with matplotlib.pyplot
- pl --> plt

* docs: removed pylab references from comments

- replaced with matplotlib.pyplot
- pl --> plt

* docs: removed all pylab references

- replaced with matplotlib.pyplot
- pl --> plt

* refactor: Replace pl with plt

- replace instances of pl (as on import pylab as pl)
  with plt (as in import matplotlib.pyplot as plt)
- mlcomp_sparse_document_classification.py clean of pl

* refactor: Replace pl with plt

- replace instances of pl (as on import pylab as pl)
  with plt (as in import matplotlib.pyplot as plt)
- plot_gpr_noisy_targets.py clean of pl
- code does not execute for extraneous reasons
  - File "examples/gaussian_process/plot_gpr_noisy_targets.py", line 31, in
      <module>
  - from sklearn.gaussian_process import GaussianProcessRegressor
  - ImportError: cannot import name GaussianProcessRegressor

* refactor: Replace pl with plt

- replace instances of pl (as on import pylab as pl)
  with plt (as in import matplotlib.pyplot as plt)
- plot_gpc_isoprobability.py clean of pl
- code does not execute for extraneous reasons
  - File "examples/gaussian_process/plot_gpc_isoprobability.py", line 24, in
      <module>
  - from sklearn.gaussian_process import GaussianProcessClassifier
  - ImportError: cannot import name GaussianProcessClassifier

* docs: removed all pylab references

- replaced with matplotlib.pyplot
- pl --> plt

* docs: removed all pylab references

- replaced with matplotlib.pyplot

* refactor: Replace pl with plt

- replace instances of pl (as on import pylab as pl)
  with plt (as in import matplotlib.pyplot as plt)
- plot_sparse_coding.py clean of pl
- code executes properly

* docs: removed all pylab references

- replaced with matplotlib.pyplot

* docs: removed all pylab references

- replaced with matplotlib.pyplot

* style: Indent properly

* style: indent properly

* style: Indent properly

* docs: Add missing .pyplot

* docs: Fix typo

* style: Indent properly