Changed structure of header. Got rid of bmp_header.c and just use bmp_header.h as a shared header file for easier separation of tasks. Updated makefile.
Merge branch 'master' of https://github.com/Trigition/PNG_File_Alteration
Changed structural component: bmp_header is just a shared header file (as in it's a subset of functions defined in bmp_top). Seperate header files are implemented to maintain modularity of layers.