0.3 Gui overhault, new nodes, value watcher

- Changed duplicate node key from shift to ctrl
- GUI overhaul
- Window states are saved
- Windows are draggable
- Windows are resizable
- Added Watch Value node (Any value type can be connected to this)
- Watched values are displayed in the small default window
- Added toggle RCS node
- Added Body Radius node
- Added Body Mass node
- Added Gravitational Constant node
- Added Time Node
- Fixed Fuel Empty Node
- Most Event nodes now can be toggled via boolean input
- Included example subroutines