"Slide X _of_ Y" instead of "Slide X _from_ Y"

Change-Id: I4e127288e788d8ac9e37330068fc694f539e1c14
Some grammatical and stylistic improvements.

Change-Id: Ia835b98c2eae6edbe152cb69302fe264eeaaf61a
Explicitly name the laser pointer in menu options.

This feature is most commonly referred to as a laser pointer (by users),
and this makes it much easier for users to discover it.

Change-Id: Ie5bc4a27194c43ed76a4a17a1eac0996a9380f8d
Move slide-displaying fragments into own package.

Lets make the relationships more obvious to anyone looking at this.

Change-Id: I2dc6e5ee429b375e83ae9d9bffc63e924ebbce07
Use AbstractSlideFragment for Grid fragment too.

This will also make it simpler to add a "current slide"
indication to the grid view.

Change-Id: If9be054a36c2422faf674d27cd856ed4d168157f
Simplify construction of the human-readable slide number.

Change-Id: I75f2f87bd7f3f98b8c4d38506207b227239137bc
Highlight the current slide in grid view.

Change-Id: Ide501f86f1cb3132287a78ccf256587e14cb3f6d
Update the slides-grid highlighting when slide changes on server.

Change-Id: I3eb7c0525976889fa84ff4d26ec9f3f93ca182a7