Survey (Grid) Zoom with a trackbar + Left mouse PAN

Added:

Ability to zoom with the trackbar. (like in flightplanner or the main MP maps)
Ability to PAN with the left mouse button.
Fix border and footprint colors.

Last part of Issue: #563

![zoom](https://cloud.githubusercontent.com/assets/3828006/3885622/a8726fca-21c6-11e4-93ff-d41c18ae1985.png)

![colors](https://cloud.githubusercontent.com/assets/3828006/3901129/e2f1dc0c-229e-11e4-9a13-be47ce32c00b.png)