Symbol protection

[WebFreak001]

Moves protection into DSymbol

Needed for dlang-community/DCD#598

[WebFreak001]

this is not strictly part of the protection changes, I added it for the use-case of after checking protection in DCD

[WebFreak001]

I don't think this is a very complex change, it just makes the protection available inside a DSymbol. Memory usage per DSymbol would maybe rise a little bit (or well, freeing SemanticSymbol won't free the few protection bytes anymore) but I don't think that would be that big of an issue? Before it was in SemanticSymbol. It was also the only property in there that was only related to the DSymbol instance, so I think it even makes sense from a semantic view to move it into DSymbol as it describes it.

@Basile-z what do you think?

[ghost]

I'm struggling on what the other IDEs do. Lazarus do show private members. I don't remember what Delphi did, and otherwise I don't know. I think that this change was proposed by @CyberShadow initially. In other words, I wont be a decision maker here.

[WebFreak001]

for the dsymbol PR here I don't think any of that matters, it simply adds information about the visibility level of a symbol. I think this should be merged and a decision on hiding private members should be made on the DCD PR.

[ghost]

tagged v0.7.0 since this modifies the API