  This paper circulated previously in a draft version. Now, upon general
request, it is about time to distribute the more detailed (and much longer)
version. The main technical issues revolve around the fine structure of the
compactification of the moduli spaces of flow lines and the obstruction bundle
technique, with related gluing theorems, needed in the proof of the topological
invariance of the equivariant version of the Floer homology.
