v0.5.0 Release

• Added support for function tokens.
  Function tokens are similar to identifiers but in addition accept a list of arguments enclosed in parenthesis (). The function arguments must be separated by comma (a single trailing comma is also allowed) and each argument can be an identifier, quoted text, number or another nested function (at the moment restricted up to 2 nested).
  Example: test(), test(a.b, 123, "abc"), @a.b.c:test(true), a(b(c(1, 2))).