Update API, add more documentation on AdaptiveIconDrawable

and fix multiple miscellaneous bugs.

Bug: 37079814
Bug: 37100106
Bug: 34829216

Test: $ runtest --path=frameworks/base/core/tests/coretests/src/android/graphics/drawable/IconTest.java
Test: $ runtest --path=frameworks/base/services/tests/servicestests/src/com/android/server/pm/ShortcutManagerTest1.java
Test: $ runtest --path=frameworks/base/core/tests/coretests/src/android/grpahics/drawable/AdaptiveIconDrawableTest.java

Change-Id: I0f5b2232853031bf3860ebea2736e894d17e4d2e