Update plot_svm_regression.py

library imports have been moved to top of the file.
Now capable of treating sample_weights in feature space
[DOC] Updated install instructions for Arch Linux

Packages are available in the official repositories for Python 2 & 3
Improved plot digits classification example.

Made two for loop statements more readable by introducing local variables.
<MRG> Doc generation works in Python 2 and 3

Documentation can be generated using Python 2 or Python 3 and sphinx
FIX Move pooling_func to constructor.
[MRG] Addressed comments
Ridge regression now can use sample_weights in feature space. Summary commit over around 20 commits to avoid failing tests
FIX: AdditiveChi2Sample can be initialized with sample_interval, #3068
Fix merge conflict and missing URL ref in whats_new.rst
[MRG] Addressed comment, fixed open-ended except

Except wile opening a URL now only catches AttributeError, eliminating an issue when
running Python 2 without internet connection.
DOC Fix ``copy_X `` default in documentation

The code uses ``True`` as the default, but the documentation incorrectly
stated that ``False`` was the default.
Merge pull request #3070 from luispedro/fix-enet-doc

DOC Fix ``copy_X `` default in documentation
Merge pull request #3062 from abatula/archlinux-install-doc

[DOC] Updated install instructions for Arch Linux
More Py3 fixes for sphinx build
Merge branch 'python-3-sphinx-fixes'
Merge pull request #3063 from chalmerlowe/improved-digits-example

[MRG+1] Improved plot digits classification example.
added tests for sparse matrix inputs to BaggingClassifier and BaggingRegressor
open iris files with  statement to avoid ResourceWarning
FIX: One more PY3 fix in the documentation generator