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- Allow selecting multiple streams
- Allow renaming streams from clip properties panel

Related to #660

Related to #382

Related to #660

Don't reload clip on audio channel change (fixed in MLT > 6.20)

46ebd11e6 in qtbase removed the (int, QString) overload again and
un-deprecated the int overload.

add getExtensionsFilter helper

Ensure we don't insert thousand separator in number conversion, and only send integer coordinates on keyframe import.
Related to #510

Summary:
* Search -> Search.. (KDE HIG)
* renameAction in Clip Menu and not only in right click menu from the project bin
* Typos

Test Plan:
Compile and run

For the moment the renameAction still don't appear in the clip menu
Could need some help figuring it out.

Differential Revision: https://phabricator.kde.org/D20971

Fix crash on thumbnail creation (resetting producer while creating thumbs)

Restore exact timeline position on project open

Audio or Video for a bin clip can now easily be disabled from clip properties, simplify stream selection

Fix Force duration cannot be disabled

enable/disable option in clip properties when changed in project settings
Fix proxy file not deleted on abort job
Don't reload clip on projy job abort