Capped image quality, remaining pan, visible source area, SCALE_TYPE_START

• Breaking change Minimum supported SDK has changed from 10 to 14. This was required to add the new EXIF support library.
• Default behaviour change Image quality is now capped at 320dpi (approximately retina quality) instead of matching the screen's density, which results in high memory use and poor performance when displaying large images on very high density screens. The difference in quality is usually unnoticeable, especially with photos. Use setMinimumTileDpi(int) to override the default.
• #273 #295 Added minimum scale type SCALE_TYPE_START. This displays the image filling the view width and height, and scrolled to the top left.
• #284 Double tap is now always interpreted as zoom when zoomed out, to avoid problems when minimum and maximum scale are very close.
• #298 Added getPanRemaining(RectF), which exposes the pan remaining in each direction, in screen pixels.
• #329 Allow OnClickListener to work before the image has loaded.
• #331 Added methods to convert view coordinates to source file coordinates to enable the visible area to be extracted from the source image. visibleFileRect(Rect) and viewToFileRect(Rect, Rect).
• #344 Guard against null vFocusStart in animation.
• Improved debug overlay.