[GRASS5] Update: 5.0.3-cvs -> 5.3.0-cvs

[Markus Neteler]

Hi,

I have modified the VERSION file in CVS:

5.0.3-cvs -> 5.3.0-cvs

The current (and desired) situation is now:
We have

 - 5.0.3 release_branch (RC3 at time, waiting for release)
 - 5.3.0-cvs: new PROJ engine, modified NVIZ, G3D updated
              tons of fixes
 - 5.7.0-cvs: former 5.1, new vector engine, DBMS support etc

The 5.7.0-cvs instructions should refer to 5.3.0, I tried to
update the relevant texts such as INSTALL etc.

Please make further updates if needed.

After getting 5.0.3 out of the door we should consider a
first 5.3.0 and also 5.7.0 release.

Markus