BUG: fix broken UPLO of eigh in python3

UPLO was cast to bytes and compared to a string which is always false in
python3.
closes gh-3977
BUG: reject invalid UPLO with ValueError in eigh/eigvalsh

to prevent unintentional use of wrong function. Restores 1.7 behavior.
Merge pull request #3978 from juliantaylor/py3-eigh-bug

BUG: fix broken UPLO of eigh in python3
MAINT: dotblas: factor out all gemm and gemv calls
MAINT: Refactor eigh and eigvalsh and associated tests.

Do not convert the UPLO argument to a bytestring, it is not necessary.
Distribute parts of the eigh tests into the appropriate TestEigvalsh or
TestEigh test class.
Merge pull request #3982 from charris/refactor-eigh-eigvalsh

MAINT: Refactor eigh and eigvalsh and associated tests.
DOC: Add list of authors to 1.8.0 release notes.
Merge pull request #3989 from charris/add-authors-to-1.8-notes

DOC: Add list of authors to 1.8.0 release notes.
BUG: fix handling of infs in hypot on windows

On any platform where we used our own implementation of hypot, (e.g.
windows) there were several issues with infs.

hypot(inf, y) == inf, for all y including nan.  We now check for inf and
handle this case explicitly for all y instead of just y = nan.

Although hypot(inf, 0) was correctly returning inf, it was incorrectly
raising the invalid floating point exception.

Fixes gh-2385
Merge pull request #3992 from ewmoore/winhypot

BUG: hypot(inf, 0) shouldn't raise a warning
Allow checking two or more fortran compilers instead of one.
DOC: add 1.7.2 release notes
Merge pull request #3997 from juliantaylor/release-notes

DOC: add 1.7.2 release notes
MAINT: Don't use 'import *' in lib/test_twodim_base.py.
ENH: lib: Rewrite vander: make it faster, and add an option to specify the order of the powers (either decreasing or increasing).
MAINT: lib: remove unused imports and PEP8 clean up in twodim_base.py
MAINT: lib: Add a 'See Also' section to the vander docstring, and make a few more PEP8 tweaks.
MAINT: lib: Use a consistent PEP8-compliant import style in twodim_base.py and tests/test_twodim_base.py.  Also make a couple more PEP8 tweaks.
Merge pull request #3999 from WarrenWeckesser/vander

ENH: lib: Rewrite vander
DOC: update 1.7.2 release notes

add two additional fixed bugs