BLD: add numpy requirement to metadata if it can't be imported.

This should help Buildout users.  Closes gh-3379.
Corrected the theilslopes implementation and added a test
MAINT: remove most references to symeig and move lobpcg benchmarks out of the test directory
MAINT: remove the rest of the symeig references
DOC: move docs from __init__.py to the lobpcg docstring
Moved implementation to `stats.theilslopes`. Added tests to `stats`.
Added y ties term to the confidence interval calculation.
PEP8 fixes
BLD: add minimum required numpy version to build_requires if numpy not found.
MAINT integrate/odepack: kill dead Fortran code
BENCH: lobpcg vs. eigh mikota pair benchmark now works
BENCH: let the preconditioner do mat-mat explicitly, not just mat-vec
BENCH: resurrect another lobpcg benchmark
MAINT: remove unused imports
MAINT: change variable names that used incorrect terminology
MAINT: remove the '__main__' section and the X.txt file from lobpcg
TST: the '__main__' lobpcg.py code is now a real test
MAINT: minor cleanups to stats.theilslopes.

Add complete references, reST formatting, PEP8, etc.
DOC: add example for stats.theilslopes.
DOC: remove docstring of stats.mstats.theilslopes, use stats version.