v0.1.0 released

Key features of this release are exporting to Windows, and game controller support.

Used to create the updated "Whiplash Taxi Co" game which I'm releasing shortly.

Full release notes:

• Export to Windows executable (command "Export as Windows Application").
• Game controller support.
• Multi-line string literals.
• New interval function overload to update gamestate at a fixed rate, dropping render frames if necessary.
• Reworked keypress logic to use keyboard buffer queues. (One for scancodes, and one for characters). This is a breaking change in that keypr is no longer a runtime function. Use getkey and getchar instead.
• New clearkeys function to clear the keyboard buffers.
• Fixed op-code optimisation bug that could produce incorrect code.
• Fixed boolean expression not requiring a boolean value.
• Ternary operators ? and : (e.g. size = n > 5 ? "big" : "small").
• Disallow variables with the same names as runtime functions.
• Add missing KEY_ESCAPE constant (for keyboard functions).
• Save text to file.
• Save/load memory blocks to/from file.
• Compiler directives for heap and stack size, window title.
• Added missing runtime functions to documentation.