Launcher3: Icon pack support

Some love for Launcher3 users
based on CMs Trebuchet

PS4
Add iconMask/iconBack/iconUpon/iconScale support

Change-Id: I2c3d29cfbceca060defd53980244e90dc46eb322
Merge branch 'android-4.4' of https://github.com/omnirom/android_packages_apps_Launcher3 into kk4.4