Changed handling of empty source list on dll_copy - not an error
Fixed a bug with iterators_id when there were multiple instances of lists, and some others (look below)

	Changelog:
		[*] Removed static iterator_id from method and added it to the list struct, as it
		resulted in erroneous behaviour when multiple lists were used
		[*] Added some more-descriptive prints for the tests at demo.c
		[*] Updated gitignore
Changed ADT type, from dllistptr to List, renamed filenames to a more C-like way
Cleared some of the api code and documentation
Merged iterator-functionallity, improved documentation

	Changelog:
		[*] Updated the master branch, with the iterators functionality
		[*] Changed dllistptr to list_t
		[*] Renamed API files
		[*] Improved documentation (broken down to 4 files in total)
		[*] Added copy list method