gp interface help should use extended help text (from "??")

[cwitty]

<wstein> 
 The new ?? help looks quite nice. It would
 be good for gp.foo? to use it.

The idea is that

sage: foo = gp(x)
sage: foo.polroots?

should use the help text from the gp command ??polroots.

The obvious approach is to change '?%s' to '??%s' in gp.py's help() method. This doesn't quite work, for two reasons:

1) gphelp carefully formats the text to fit in the current line width, and then Sage displays this text indented; so almost every line wraps.

2) gphelp uses control characters to make words bold, underlined, etc.; when the help is viewed from the notebook, these control codes are visible in the output, and look very ugly.