function pointer parser

[mwichmann]

Once we recognize that a struct member is a function pointer, it would be nice to
be able to break apart the string so we can make use of it. Given that we have
split a line into a pair as in this example:

type: void
name: (* value_changed) (GtkScaleButton *button, gdouble value)

We want to break the "name" string into:

• name entry in TypeMember: value_changed
• Type for this fptr: (*) (GtkScaleButton *, gdouble)
• members of fptr type: GtkScaleButton *button, gdouble value
  which for looking up the type first and then adding the field, need to
  be further broken into type/name correctly.

[mwichmann]

So far, we're now pulling out the member name ("value_changed" in the example), and also returning a string which is "the rest of the line" (less the enclosing parens). Further decomp needed, comments to this effect are in the code.