build: remove use of submodule for dvb-scan data

Revert back to manually fetching, though now its a git report its somewhat
simpler and we'll avoid using a separate script.
build: correction to ensure old data is removed.
timeshift: fix start of buffer bug and add some useful debug.
timeshift: fix printing error.
libav: detect versions that are to old for libav muxing
build: ensure proper path is cleaned of .git files.