Issue #97: improve support for sparse row array
Issue #61: clean up temporary files in case of crash during parsing.
Version bump to 2.5.6
Version bump
Merge branch 'master' of github.com:weshatheleopard/rubyXL into comment_support

Conflicts:
	lib/rubyXL/parser.rb
Issue #46, #102
Issue #46, #102
Merge pull request #114 from weshatheleopard/names_in_space

Names in space
Merge branch 'master' of github.com:weshatheleopard/rubyXL into comment_support

Conflicts:
	lib/rubyXL/objects/content_types.rb
	lib/rubyXL/objects/relationships.rb
	lib/rubyXL/parser.rb
	lib/rubyXL/workbook.rb
Moving nil check to a better place
Version bump to 2.5.7
Regenerate gemspec for version 2.5.7
Merge branch 'master' of github.com:weshatheleopard/rubyXL into comment_support

Conflicts:
	lib/rubyXL/objects/content_types.rb