I pushed a first pass on the master branch. I removed most of unused variable, unused static functions (not in generated files), implicit function declaration, untyped functions and vars warnings, plus some miscellaneous ones.
I didn't touched most of warnings related to gtk deprecation, pointer casting (gpoint to int, int to gpointer), and macros, for the moment.
I commented unused functions, and tagged theme with UNUSED. Could you grep this tag and check if function may be used later, or delete them ?