Library that provides API used by LO-based apps on touch devices

This is all very much a work in progress and the design can change radically
at any moment. The name "touch" for this module and the library name
"libotouch" are not fixed and might change if somebody comes up with niftier
names.

This module will contain an UNO API to be called either from Java (for
Android), or directly (iOS). (Or, on iOS, possibly through some thin
Objective-C layer to hide the UNO.)

The API will provide a mechanism to render "tiles" of a document at some
requested zoom level. Initially for viewer style apps, but the work should
ideally be open-ended to potentially be a base for editing apps, too.

For starters, concentrating on text ("Writer") documents as they are
easiest. With spreadsheets come the added complexity of the cell grid being
potentially unbounded and no clear "page" area. With presentations come the
animation complications, and possibly LO-based viewer apps for presentations
will be done in a totally different fashion.