Contrary to the MSDN, you can 'create only' whilst using a previous value
(ie +-variable and [~];value). This breaks the install of an application
I was debugging who uses that throughout for all their variables. In
addition whilst adding some tests I've also cleaned up invalid prefix
syntax handling and semicolon removal if the original string is empty.

rpcrt4: Add structure definition for RPC AUTH3 packet and use the size of this on sending to fix authentication against native servers.

Also use the new size to validate incoming AUTH3 packets to be
consistent with native.

The current regular expression causes all letters and spaces (among
other characters) following the appearance of a digit to be classed as
a literal, including C identifiers which may need to be expanded.

The expression was intended to catch the remaining characters that
were not covered by the first two rules ([^a-zA-Z0-9'"#/\\\n]+ and
{cident}), but the [^'"#/\\\n] expression caught {cident} as well.
While one solution would have been just to catch the expression that
match [a-zA-Z0-9]* that don't match {cident}, i.e. [0-9][a-zA-Z0-9]*,
in the interests of avoiding unnecessary multiple LITERALs being
generated and then combined during parsing the expression also
includes the first expression, making it
[0-9][a-zA-Z0-9]*[^a-zA-Z0-9'"#/\\\n]*.

It takes an event type, not a manual reset flag.