Better blockly code representation than XML

[jirmauritz]

• replace XML by abstract syntax tree in JSON, postfix, ...
• write function to convert XML to the new representation (blockly returns XML anyway)
• ideally write inverse function back to XML to be able to reconstruct blockly programs

[effa]

Some thoughts on the JSON representation:

1. most compact, while still readable representation I can think of:

[forward, [turn, left], [repeat, 10, forward, [turn, right]],
[while, [check_color, not, yellow], forward]]

1. "object per block" - less compact, but more explicit and probably easier to work with:

[
{command: 'forward'},
{command: 'turn', args: ['left']},
{command: 'repeat', args: [10], body: [...]
]