Add README

Signed-off-by: David Sterba <dave@jikos.cz>
Fix build issues

- add force to ln
- adjust linker paths
- skip pkg-config for libelf
- build lib in the same directory
- externa libdir and bindir
- use pkg-config where possible
- gtk 3
- reorder objects for linker

Signed-off-by: David Sterba <dave@jikos.cz>