Explicitly allow trailing bytes when parsing WKB

[peterstace]

There is no check for trailing bytes when parsing WKBs. This should be an error case, since it represents a malformed WKB.

[peterstace]

It seems as though it's better actually not to detect this case and give an error.

Some Esri productions do (or at last did) produce WKBs that contain trailing bytes. There is nothing in the OGC spec that actually states that trailing bytes are not allowed.

See this stackexchange: https://gis.stackexchange.com/questions/29432/a-bug-in-esri-line-geometry-wkb-that-adds-needless-trailing-0s-behind-otherwis

So what we probably want to do for this issue is to add some unit tests to show that trailing bytes are actually allowed (and ignored).