add record placeholder icon
add record icon to icon bank
implement record mode
follow playback cursor in record mode
stop recording on silence button
Merge pull request #259 from cyberixae/implement_recording

Implement recording
Add first iteration of module saving task.
Store module path in session.
Implement default task executor.
Add saving support to the module object.
Add save button.
Set command line module path as the save target.
Rewrite task execution, disable UI when saving is in progress.