When starting a thread, put old thread at end.

This matters so the right thread is run later when scheduling switches
back.
If the mipscall id doesn't match, don't create.

Fixes a crash when savestating.
Implement sceMpegFlushAllStream().  Fixes FF7CC.
When no packets to decode, return no data more.
Fix logging typo.
Only alternate buttons, not arrows/special keys.
Merge pull request #1136 from unknownbrackets/input-fix

Only alternate buttons, not arrows/special keys
Merge pull request #1137 from unknownbrackets/mpeg-fix

Fix sceMpegFlushAllStreams() + minor
Merge pull request #1138 from unknownbrackets/scheduling

Fix scheduling when starting a thread + potential crash
Merge pull request #2 from hrydgard/master

Sync