fix include header path
use sylplugin_factory_source_dir variable
define SYLPF_ID and SYLPF_OPTION
override predefined constant
avoid strict aliasing cast rules
cleanup macro definition
TODO: implement save option
fix type mismatch

Because header list must be stored into GSList pointer
fix type mismatch
add utility macro
avoid strict aliasing
initialize window
force cast to proper type
add missing  "src" directory