[Android] save unsent text messages as draft
Issue generated from Tuleap's migration script. Originally submitted by: Simon Désaulniers (sim590)
When writing a message in the chat window and you leave the chat window for coming back after, you realize the text you wrote is gone.
This a common thing to exit the chat window to go and copy some text elsewhere from another conversation and then complete your draft message in the initial conversation. The desired behavior would be much like the one you get in other android messaging apps: when leaving a conversation with text in the textbox, the text is saved as draft. A conversation in draft is also visually differentiated from a conversation not in draft.