Too much whitespace was getting deleted

In several places the code was using Apple's whitespace for deletable
whitespace, but it should have been using the internal
ignoreableWhitespace.
Merge pull request #619 from JasonLion/master

Too much whitespace was getting deleted
added isEqual to compare paragraph styles
Added list round trip tests #618
Also check secondary paragraph style after prefix #618
improvements for #618
Added DTCoreTextTestCase as place for useful utilities
Added unit test for #623
added test for missing innermost /LI
corrected unit test for #623
Don't close LI if a deeper list follows,
fixes #623
Merge pull request #624 from Cocoanetics/od/issue_623

Fix for nested list output
Merge branch 'develop' into od/issue_618

Conflicts:
	Core/Source/DTHTMLWriter.m
	Demo/Resources/CurrentTest.html
Added list style range check
fixed iOS 7 problem with -isEqual:
added NL
changed list range checking to look for instance, safer than containsObject since we are looking for the identical instance
#618
changed range searching to look for instances instead of isEqual:, should be faster
cleanup
Merge branch 'od/issue_618' into develop