Modularized Prelude And Improved Error Reporting

0.3.1 (2019-09-16)

• Incompatible Change: Removed create_wlamba_prelude() and added proper
  module support instead. Splitted up the prelude into a core part and the
  standard library utility functions. With !@wlambda you can import the core
  language globals. With !@import std std you import the standard library.
• Feature: re:match added.
• Bugfix: Errors weren't properly propagated by the threads::MsgHandle.
• Change: Error reporting for arity mismatch contains the position of the
  function definition and the position of the call site.
• Feature: Added std:append and std:prepend.
• Change: Enhanced stringified version of a function.
• Feature: Added apply [[@]] syntax for applying a function to a vector of arguments directly.
• Change: Defined equality with == for everything.
• Doc: Documented bool data type.
• Bugfix: Fixed evaluation order of function arguments.
• Feature: Implemented VVal::ref_id and std:ref_id which returns a
  unique 64bit signed integer dependent on the memory ID of the value.
  This is only useful for reference types, where the storage location of a
  value doesn't depend on the stack.
• Feature: Made stringifying of WLambda data cope properly with cyclic data
  structures, this makes printing objects with closures work without
  locking up your script.
• Change: Greatly enhanced error message file position reporting and
  panics have better backtraces now.