Issue #106: some readers do not understand attributes that contain ''
Version bump to 2.5.2
Updating rdoc
Regenerate gemspec for version 2.5.2
Further Issue #106 fix
Minor cleanup
Moving accessors to their permanent place of residence
Properly saving the formulas
Issue #107: adding compatibility trimming for sheet names
Version bump to 2.5.3
Updating rdoc
Bundle update
Merge branch 'master' of github.com:weshatheleopard/rubyXL into comment_support

Conflicts:
	lib/rubyXL/objects/content_types.rb
	lib/rubyXL/objects/worksheet.rb
	lib/rubyXL/worksheet.rb