0.1.20

• JavaScript backend!
• Hundreds of C warnings were fixed. gcc v.c now builds without
  any warnings.
• The mutability check now applies to function args (mutable
  receivers that are not modified result in a compilation error).
• V tests now show how long each test took.
• Official Android support (only console applications via Termux for now).
• Typo check. If a variable/function/module etc is misspelled,
  V will suggest the correct name.
• Lots of Microsoft C fixes, and a separate Travis instance for
  this backend.
• Bitwise operators |, ^, & no longer work with booleans.