r948: Tridge suggested that the best way to write the ethereal parser is to

r948: Tridge suggested that the best way to write the ethereal parser is to
base it on the generator for the ndr pull/push code rather than trying
to get all the alignment and other junk sorted out by hand.

This commit (nearly) gets eparser to the same state it previously was
but based on parser.pm.  We correctly parse simple types, strings and
sids.
(This used to be commit 6739cd5fdd353c575626cbfbc6339a8a6908daf7)