Read timer: various improvements
Read timer: various improvements

* no timeout on alarm
* autoclose menu when starting timer
* show time in menu when active

Markismus/koreader,lgeek/koreader,Frenzie/koreader,pazos/koreader,koreader/koreader,koreader/koreader,Hzj-jie/koreader,mwoz123/koreader,poire-z/koreader,houqp/koreader,mihailim/koreader,Frenzie/koreader,NiLuJe/koreader,poire-z/koreader,NiLuJe/koreader,apletnev/koreader