misc: scan_scripts.c: Add subtitle scripts
misc: scan_scripts.c: Add subtitle scripts

Other:
* m_scan_scripts: rewrite: eradicate the if-blocks
* _script_new: free file contents buffer
* _chk_script_ident: Revise

Signed-off-by: Toni Gundogdu <eac2284b3c43676907b96f08de9d3d52d5df0361@gmail.com>

legatvs/libquvi,legatvs/libquvi,legatvs/libquvi