Implemented basic C++ support

[Ellen-Wittingen]

This is the ground work to later support SYCL constructs (which I will start on after the summer holidays).

I implemented the following C++ constructs:

• if-statements, while-loops, and for-loops with the following structure: for (int i = 0; i < max; i++) {}
• math operators a + b, a - b, a * b, a / b, a % b, a++, a--, a += b, a -= b, a *= b, a /= b, a %= b
• logical operators !a, not a, a && b, a || b, a == b, a != b, a < b, a <= b, a > b, a >= b
• methods similar to the c implementation, allows abstract and fully implemented methods, and for them to be called
• variable declarations, both local and global
• arrays to the same extent as the c implementation. Elements can be assigned and read from arrays that are functions parameters.
• pointers to the same extent as the c implementation. So declaration of pointers, but not getting their address with &
• declaration and usage of namespaces
• scoped blocks inside methods
• the types bool, int, long, double, float, char, and void (literal string are recognised, but do not have the type char*, so cannot be used in practise)

See the files in examples/cpp/* for example usages

Also added a setup to implement SYCL class methods in the future. Implementing classes is to much work so I want to handle the sycl class methods I need in the following way: In the name resolution phase, when searching for what a name refers to, if in the name . is detected (so when it is a reference to a method or field of a class), the type of the name before the . is found (so the class). If the type is one of the supported sycl classes, the name is replaced with the namespace path to an equivalent method in a namespace in res/universal/res/cpp/sycl/sycl.hpp. For example, in

sycl::queue queue;
queue.submit(5);

queue.submit is replaced with VERCORS::sycl::queue::VERCORS__submit, which is declared in the custom sycl header file in res/universal/res/cpp/sycl/sycl.hpp. The name VERCORS is added in front of the namespace and methods to make them unique from user-defined c++ code, as method overloading is not supported.

See examples/sycl for an example of usage, res/universal/res/cpp/sycl/sycl.hpp for supported SYCL methods (only contains 2 methods for testing purposes at the moment), and src/col/vct/col/resolve/lang/CPP.scala line 89 and onward on the just described handling of sycl class methods.

[pieter-bos]

Looks good! I'll merge this immediately for the benefit of not accumulating merge conflicts over summer break, the comments can be addressed later.

[pieter-bos]

I think this can be simplified if we add a node for ::, the left-hand side can then typically be resolved to a RefNamespaceDefinition. The right-hand side is then just one step: looking up a name in the (already resolved) namespace. I think this is fine for now though, we can discuss it more later.