rename to erfa_generator and fix file names in docs
style tweaks in erfa_generator.py
remove unicode_literals from erfa_generator

In py 2.x, unicode_literals makes the generated strings look like u'foo',
instead of 'foo', as they do in 3.x
minor typo fix
doc updates to the templates
rename of erfa sub-modules to core
update auto-generator to use erfa_generator instead of cython_generator
update template to make documentation more astropy-ish
For NPYLT1P8, use reshape rather than getitem for scalar erfa output
Add ERFA generated files to .gitignore
typo fix
Merge pull request #3173 from eteq/erfa-tweaks

ERFA wrapper updates