Markers - additional UI + zooming fixes, distance while dragging marker

Markers: 
- added optional detail line to label w/ translucent background for contrast against a variety of backgrounds
- markers with text can now be any color - generated from single bitmap resource (better bitmap welcome :) )
Replacement color is white. 
- display info window with distance from previous point on flight path while dragging 

Zoom:
- zoom to fit including marker not just coord 
- exclude points w/ uninitialized coords from bounded region - uninitialized points (0,0) not usually significant when planning but make zoom less effective than it should be. 
![screenshot_2013-09-30-20-55-19](https://f.cloud.github.com/assets/4014433/1242221/d1c5a294-2a36-11e3-86b7-176279b0249d.png)

![screenshot_2013-10-01-01-30-31](https://f.cloud.github.com/assets/4014433/1243016/a42656e8-2a5a-11e3-9eda-d1ecbc25dd99.png)

Please see commit comments.