named parameter support for custom functions

[sempare]

allow custom functions to be called, something like:

<% doPrint({ "name" : "peter", "age": 10}) %>

Args can be in any order:

<% doPrint({ "age": 10, "name" : "peter" }) %>

function doPrint(const name:string; const age:integer) : string;
begin
    exit(format('%s %d', [name, age])];
end;

[sempare]

may be useful for following use cases:

• to even allow for dict to json type functionality,
• allow for data to be passed around templates more efficiently

[darnocian]

related branch is json_support, but will need to review as it is quite old

[darnocian]

v1.7.2 includes the initial json / map like variable support, but doesn't support passing to functions yet.