Heavily refactor gcoder to trim memory consumption again
Don't parse S and P parameters for all glines as it's a minor parameter

Add a specific parser for these, which can be accessed as gcoder.S/P
Remove code duplication in parse_coordinates
Store current_tool in the upper bits of status to save 8 more bytes
More refactoring of gcoder argument parsing
Add memory leak warning
Merge branch 'experimental' of github.com:kliment/Printrun into experimental
Switch to orthographic projection
Fix zooming using keystrokes in gcview