BUG: runtests: chdir away from root when running tests

This makes it possible for subprocesses possibly launched by the test to
import the module under testing.

Also, do not pass --debug to setup.py build, since this can make the
build require Python debug symbols to be installed (on windows).
DOC: linalg: don't recommend np.linalg.norm
Merge pull request #2986 from pv/runtests-fix

BUG: runtests: chdir away from root when running tests
Add Eclipse editor project files to .gitignore
Add parenthesis in csgraph tutorial title to be consistent
Add missing return statements in Python 3 kdtree code
Remove statement without effect in mstats_basic.py
Remove duplicate method in weave/base_info.py
Fix variable name typo in weave/cpp_namespace_spec.py
Fix dblint function (variable names incorrect) in fitpack.py
TST: spatial: KDTree.node ordering

This was fixed in 6c618a3b61f3d4c4342427c94f299bd25057227a.
TST: add basic test for fitpack.dblint, it was completely broken before PR-2942

Also convert some docstrings added to tests in a previous commit to comments.
Merge branch 'pr/2942' into master.

See https://github.com/scipy/scipy/pull/2942
Merge pull request #2987 from larsmans/scipy-not-numpy-norm

DOC: linalg: don't recommend np.linalg.norm