[purge.c] in the pruning step, remove only half of the excess at a time. 	  This gives a smaller matrix. For example on a c143 with (before 	  the pruning): nrels=12904878, nprimes=12267033; excess=637845.
[purge.c] in the pruning step, remove only half of the excess at a time.
	  This gives a smaller matrix. For example on a c143 with (before
	  the pruning): nrels=12904878, nprimes=12267033; excess=637845.

	  Before that change we got at the end of the pruning:
	     nrel=9411908, nprimes=9411748; excess=160
             WEIGHT: 179981518 WEIGHT*NROWS=1.69e+15
	     
          Now we get:
             nrel=9140920, nprimes=9140760; excess=160
             WEIGHT: 174886795 WEIGHT*NROWS=1.60e+15


git-svn-id: 189946a10c5fc96e9dd03ba7cba917cd4c3d09f4@1802 de4796e2-0b1e-0410-91b4-86bc23549317

mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs