Add mad_compile:xyrl_files/1 & support compiling xrl files
Return true in mad_compile:is_compiled/2 if Target's mtime is equal-greater than Source

Don't compile xyrl files if they are compiled already
Add mad_compile:files/1,sort_files/1,split_files/1

remove xyrl_files/1 erl_files/1 app_src_files/1
use mad_compile:files/1 for gathering files