insert more extensions

BetaFeatures
CategorySlideShow
DataTypes
Flow
FlvHandler
MassEditRegex
MassMessage
PushToWatch
Serialization
ValueFormatters
ValueParsers
ValueValidators
ValueView
WhichImageIsBetter

Also fix 'branch = .' indenting for Calendar in .gitmodules.

Change-Id: Id0346b4f4d790f5395a12c1a999b0e94ad4d46fa