Finalizing work before pre-release 4

New methods added to help with modular design of handling/printing tech

upgradeTech modified to be a little cleaner (no switch statement required,
all work is done through other methods to get desired values straight away).

getUpgradeLevel() added
getUpgradeMaxLevel() added

Added these:
public readonly int maximum_levelMaxDistance
public readonly int maximum_predictionAccuracy
to main RoverScience class. Will now be accessed through
getUpgrade methods for maximum use of enums

ScreenMessages added to convey max level / not enough science

UpgradeGUI added to GUIClasses, now being drawn in drawGUI
Some shit I missed