Keep the same height for messages in the list

Height and overflow properties are added to message items in order to
keep the size of each line of the message list the same.
Before this patchset, long untranslated messages presented the problem shown at http://i.imgur.com/h6Xaj.png

Change-Id: I3597c289d45dea5ef15b28666951ad25927a44b8
Merge "Keep the same height for messages in the list"