Add support for unary plus

[tinygiant98]

This change provides support for unary plus operations for constants and variables. This allows constructs such as +7, +x, (+7 + +x), etc. The result can also be passed directly as a function paramater or used within a conditional: my_function(+x), if (+x) {}, while (+x) {}, etc.

Addresses #127 and #57.

Testing

Tested the following constructs:
+<variable|constant>
some_variable = +<variable|constant>
my_function_call(+<variable|constant>);
if (+<variable|constant>) {}
while (+<variable|constant>) {}
some_variable = [+]<variable|constant> <+|-> [+]<variable|constant>;

Changelog

Added

• Added support for unary plus operations

Licence

• I am licencing my change under the project's MIT licence, including all changes to GPL-3.0 licenced parts of the codebase.