Add trimmed option to blocktrans, blocktrans trimmed
option removes newlines from contents of blocktrans
and replaces any whitespace at the beginning and end of a line into
a single space. This makes translator life easier.
More detail is described in the bug report.
Change-Id: I835167eeec4f8596cec9c906548b3fa557ed1374
Closes-Bug: #1655249