[PyQt] Change in Snapshot Version Numbers

[Phil Thompson]

I've made a slight change to how snapshots (of sip, PyQt and QScintilla) are 
versioned.

Previously a snapshot was named "sip-x.y.z-snapshot-date" where "x.y.z" was 
the version number of the *previous* release. For all new snapshots "x.y.z" 
will now refer to the *next* release.

For example, tonight's SIP snapshot will be "sip-4.7.4-snapshot-20080123".

This is also reflected in version numbers embedded in code. For example the 
value of SIP_VERSION will be 0x040704.

Of course, v4.7.4 may never get released if v4.8 is ready sooner.

Although I've no immediate plans to do so it will allow me to make available, 
for example, snapshots from a maintenance branch at the same time as 
snapshots from the trunk without them getting confused.

Phil