add standard library

[obfusk]

• [x] json
• [x] math
  • [x] abs, floor, ceil, round**, trunc, ...
  • [x] pi, exp, log, sqrt, sin, cos, ...
  • [x] :math import ?!
• [ ] io: open!, stdin, ...
• [ ] rx: rx-split, rx-matches, ...
• [ ] http: get, post, ...
• [ ] sys: get-env!, run-cmd!, glob!, ...
• [ ] more lazyness?
• [ ] ...