fix slight pyfits version issue
made the alias_dtypes explicit rather than using items from cpp_valid_dtypes, as these do not always come in a predictable order it seems
(#571)
put int Mike's suggestion
(#571)
Update aliases for int, float to specific types, rather than use zeros().dtype.type, since we don't actually have int64, so can't use that on machines where int -> int64.
(#581)
Add unit tests for Image type aliases
(#581)
add Mike's work on #571 to this branch's CHANGLELOG
(#581)

Conflicts:
	CHANGELOG.md
Added missing CHANGELOG entry for #572
implemented Mike's suggestion on #486
added a simple unit test
(#486)
resotre whitespace
(#486)
harmonize arg style
(#486)
changelod mod
(#486)

Conflicts:
	CHANGELOG.md
Fix new BoundsI constructor to still work with other forms of initialization.  e.g BoundsI()
(#486)
Add tests that args to BoundsI constructor are integer-like
(#486)
Update tests of new BoundsI constructor
(#486)
Add similar mod to PositionI constructor
(#486)
Add PositionI to CHANGELOG
(#486)

Conflicts:
	CHANGELOG.md
move metaclass assignment so that python help finds galsim.Image docstring (#593)
create failing unit test to demonstrate problem identified in issue #594
remove all the byteorder checks from fits.py, and move them into the Image constructor
(#594)