navit: change to INC_PR, bump srcrev, split icons and config for navit_svn

navit: change to INC_PR, bump srcrev, split icons and config for navit_svn

* xpm stuff is updated maybe about 6 times a year, sources are updated
  few times every day
* with navit-icons in separate package we don't need to download 3,5MB
  package, every time we bump SRCREV because of software fix
* navit-icons SRCREV will be changed only if there is new icon needed
  for newer navit SRCREV
* big package was installed by opkg really slow
* provide 2 desktop icons one with Display blanking disabled ie for car
  navigation, second with only CPU requested ie if you're using navit on
  foot or bike and want longer battery life
* splitted configs are easier to modify, also provide better defaults for
  freerunner layout

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>