Updated SDK target to v17; fixed associated issues

- Media items saved to the device's media library are now named by date
(rather than by UUID) - better usability, and retaking a picture
doesn't delete the original
- Changed the way SVG is used to ensure that drawPicture is not used
directly in onDraw (now using SVGView). As a result, now targeting the
latest SDK version (17)
- As a result of the SDK upgrade, removed deprecated methods where
possible (SQL queries remain a work in progress)
- Also due to SDK upgrade, modified VUMeter to manually draw line caps
(they don't work when hardware acceleration is enabled)
- Made audio and camera hints display less frequently (still needs
improvement)
- Fixed a playback issue on newer devices (Android MediaPlayer start is
far slower after API 4.1; now timing instead of assuming exact file
durations)
- Added an about box and link to source in preferences
- Fixed a potential crash in the text editor
- Android's uses-feature documentation is incorrect, or the Play store
filtering is broken; removed all touch screen filters (relying on
default touchscreen requirement