Fix building with --enable-debug-flags

Fix building with --enable-debug-flags

This adds wrappers for callback functions which now takes two inputs
to fix building with incompatible function types warnings. See

https://gitlab.xfce.org/xfce/xfce4-power-manager/-/issues/63

for a similar issue in Xfce-power-manager.
It also adds a header keymap_template.h and makes the char *
keymap_template non-static, and removes some un-used functions
and variables.