Improve Templates & Proxy-Reflection JSON

[TheNitesWhoSay]

While some limitation with regards to reflecting templated classes is expected e.g...

• Two partial specializations could have different fields, and thus reflecting the primary template alone can't capture all fields
• Template classes that aren't full specializations are not a type; it may be impossible to reflect templates that aren't full specializations to the same extent as regular classes

Support could be a lot better than it is at present. Also the current workaround it to use proxy reflection on full specializations, but that's not fully working with JSON, need this to be working as well.

[TheNitesWhoSay]

JSON for proxy-reflected types is looking good as of https://github.com/TheNitesWhoSay/RareCpp/pull/89

It also seems much more support can be given to templated types than initially expected, e.g. I've managed to get a simple example working on my local

template <typename T>
struct Templated
{
    T a;
    T b;

    REFLECT(Templated, a, b)
};