Clarify Lua metamethod usage for some classes; Minor docs edits

[Lyrth]

Resolves #374

• Clarified usage of __index, __newindex, __call in multiple classes, placing them in a separate Metamethods category.
• Added __len metamethod description for TArray.
• UFunction __call: mention return val and specify the need for a context parameter if not part of an object instance.
• UObject __index: added example of a UFunction call.
• UObject type(): clarify that type(object) is not equivalent.
• Minor edits (spelling)

For initial review.

[UE4SS]

I have requested a bunch of changes where the syntax is wrong but the casing is also wrong in most places.

In general, I believe we're using PascalCase for variable names in the docs and UECase for UE types, and where appropriate the UE type without the type.
Meaning that if the UE type is UFunction and if you're referring to the type then put use UFunction never ufunction, but if you're referring perhaps to the general concept of a function then Function would be fine.
I know we're a bit inconsistent with this, the UObject docs for example has this: CallFunction(UFunction function, auto Params...) and ideally "f" should've been "F" for the first param.

[Lyrth]

I have requested a bunch of changes where the syntax is wrong but the casing is also wrong in most places.

As for the indexing syntax changes, I originally intended for it to show passing in a string variable as the index (as opposed to passing in a string literal, hence the different casing and name, e.g. structMemberVarName variable vs. StructMemberName literal on the second usage).

Although on second thought, a string literal would be less confusing and better overall as it also implies that the index is a string value in general. I will make changes to those usages.

I will also make changes to the casing of the variables, e.g. ufunction(...) -> UFunction(...), and probably for ones with __index too, as in object[objectMemberVarName] = newValue -> UObject["ObjectMemberName"] = NewValue, unless the former's currently fine.

[UE4SS]

I have requested a bunch of changes where the syntax is wrong but the casing is also wrong in most places.

As for the indexing syntax changes, I originally intended for it to show passing in a string variable as the index (as opposed to passing in a string literal, hence the different casing and name, e.g. structMemberVarName variable vs. StructMemberName literal on the second usage).

Although on second thought, a string literal would be less confusing and better overall as it also implies that the index is a string value in general. I will make changes to those usages.

I will also make changes to the casing of the variables, e.g. ufunction(...) -> UFunction(...), and probably for ones with __index too, as in object[objectMemberVarName] = newValue -> UObject["ObjectMemberName"] = NewValue, unless the former's currently fine.

All your proposed changes look good.

[Lyrth]

• Applied changes
• Fixed UObject:CallFunction param casing (UFunction function -> UFunction Function)