Fix for generic tooltips constructors and methods

Generic types like System.Collections.Generic.List<T>() would fail due to
the mangled xmldoc key being T:System.Collections.Generic.List`1.#ctor etc
This was not parsed correctly as it was assuming there would be nothing
following the type parameter args `1.  Also added a parameter check in the
overloads as previously an overload would be considered a match is it wad
the same number of parameters, there was no type check of the parameter detail.