TwoFold (2✂︎f) v0.10.0-rc1

v0.10 WIP

• BREAKING change: JSON props in backticks are gone!
  replaced by the new JSX curly braces {..} props
• there is a new {..} prop type, inspired from JSX curly braces
  and it allows newlines inside
• newlines also allowed inside backtick string props
• new {...} JSX spread syntax to merge groups of variables,
  and to export groups as global variables
• created "import" tag to import set, json or toml variables from
  other files. This is EXPERIMENTAL for now.
• created "toml" tag to define variables available within the file;
  it works just like the "json" tag
• created "del" tag to delete variables, but you can also set deep
  variables to undefined