Small optimizations in EventsProxyModel

- testBit() is slightly faster than [] operator

Signed-off-by: Piotr Galiszewski <pgaliszewski@corp.bluecherry.net>
Use localtime in all computations and UI visible strings

Signed-off-by: Piotr Galiszewski <pgaliszewski@corp.bluecherry.net>
Repaint timeline after changing date

Signed-off-by: Piotr Galiszewski <pgaliszewski@corp.bluecherry.net>
Merge branch 'issue-196' of https://github.com/pgalisz/bluecherry-client

Signed-off-by: Piotr Galiszewski <pgaliszewski@corp.bluecherry.net>