Master markers - additional UI and zooming fixes

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. 

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)

Please see commit comments.