Pragmas

[degory]

Add support for pragmas.

Full support would integrate with/interoperate with DotNET attributes, but that's not needed for bootstrap.

Pragma syntax should resemble a simplified function call prefixed with @. Parameters can be limited to literal strings, numbers, booleans, and enum members. For example:

@Ghul.Compiler.output("test.il")

Required:

• Parse tree nodes
• Parser
• Way to attach one or more pragmas to definition and statement parse tree nodes
• Way to wire up a pragma name to a corresponding pragma implementation that can see all instances of its pragma in the program source (can be semi-hardwired for now, e.g. a Dict of strings mapping to implementing class instances)