map_lib string associative array - missing functions

* Added get method to get a default value if key's not found
* Added delete functionality
* Added head struct that has a name (for later use)
* Changed default return value to NULL
* Changed "map_stuff" testing code to include deleting and default values
* Added a very basic Makefile for gcc
* Added Code::Blocks stuff, binary- and .o-files to .gitignore
* Added doxygen method descriptions to header file