UCode_AX: don't always call NotifyAXThread()

StartWorking() already does this if needed
Remove unused function PanicAlertToVideo from Core.cpp.
Merge pull request #181 from lioncash/unused-core-func

Remove unused function PanicAlertToVideo from Core.cpp.
Interpreter: make some class members private
UCodes: nits
More range-based loops and overrides
.gitignore: fix the build directory pattern
Turn some non-const refs into pointers
Tests: fix signed/unsigned comparison warning
Merge pull request #159 from Tilka/misc

Cleanup stuff