Fix GradleOverrides warning by removing uses-sdk from manifest.

Gradle's defaultConfig will override whatever is in uses-sdk.
Fix AppCompatResource warning by not using android ns for showAsAction.
Fix '_' used as an identifier warning.

Use of '_' as an identifier might not be supported in releases after Java SE 8.
Fix ExtraText warning in note editor XML.
Fix ObsoleteLayoutParam warnings.
Fix Deprecated warning caused by android:editable="false".

When a simple android:editable="false" becomes android:clickable="false"
android:cursorVisible="false" android:focusable="false"
android:focusableInTouchMode="false".
Fix InefficientWeight warnings.