Update libsuperuser
Don't crash when phone is not rooted

Closing the shell throws a NPE when it couldn't be opened in the first
place. We could detect the by checking for SHELL_EXEC_FAILED explicitely,
but there might be other exceptions which shouldn't cause crashes.
Handle libsuperuser's SHELL_DIED result
Add background for installation mode text

This should give at least a little hint that it is clickable. Surely not
best solution, but better than nothing. This will become obsolete with a
redesign soon anyway.

The image is the old AOSP toast background with reduced padding.
Bump version to 2.5 beta2
Translation updates

Changes were contributed by:
  [ca] divendres (closes #115)
  [de] LibertyMarine (closes #116)
  [es] David Vaz Guijarro (closes #113)
  [ja] Noumi Ryoko (closes #110)
  [nl] GertlilyNL (closes #112)
  [nl] Leonard Simonse (closes #112)
  [sk] pyler (closes #111)
  [zh-rCN] Yeechan Lu (closes #114)
Avoid potential issues when skipping big log files

Thanks to @Tungstwenty for the heads-up.
Display translator for Arabic
Translation updates

Changes were contributed by:
  [sr] maleksa
Display translator for Serbian
Fix Lint warning by using the correct attribute name

Maybe there should be a Lint warning for such typos...
Bump version to 2.5
Fully implement Parcelable

I was previously only implementing Parcelable with the describeContents() and
writeToParcel(Parcel, int) methods, with writeToParcel(Parcel, int) being empty.
While this should 'work' for fragments, it's hacky and wasn't actually
working in some cases (I think after the activity gets destroyed by
Android when memory is needed,) which caused some FCs.
With this in mind, I could either use Parcelable or Serializable.
Serializable requires me to add two words to Module.java. Parcelable, a
bit more… That being said, Parcelable is much faster so I stayed with it.
Add ProGuard config

Obfuscation is turned off, so ProGuard only optimizes and shrinks the
code by removing unusused classes. The APK size is reduced by quite a bit.
Merge branch 'master' of github.com:rovo89/XposedInstaller into xposed-holo

Also updated proguard.txt and ignored Installation Mode TextView background
since it's been changed to a Button in this branch.