audio/cplay: Update to 1.50

• Switch to GH account used by Debian
• Update patch-cplay to remove upstreamed changes and add mpv support
• Add off-by-default dependency options for supported audio players
• Change to USES=python:-2.7; runtime testing with python3 failed
• shebangfix added to remove need for ${LOCALBASE}/bin/python symlink
• Add patch-po_fr.po to fix build error fr.po:78: 'msgid' and 'msgstr' entries do not both end with '\n'

Reviewed by: adamw
Approved by: koobs, mat (mentors)
Relnotes: https://github.com/hukka/cplay/blob/v1.50/ChangeLog
Differential Revision: https://reviews.freebsd.org/D7200