Fix regression with empty limits
Fix regression with empty limits

Before 2.6.6 and empty `limit` parameter would enable the default limit.

Since we now use General::intval, an invalid value would be converted to -1.

Fixes #2557

BloodBrother/symphony-2,michael-e/symphony-2,DeuxHuitHuit/symphony-2,mazedigital/jcilearn,symphonycms/symphony-2,mazedigital/jcilearn,DavidForster/symphony-2,bauhouse/sym-todo-list,alexnantel88/symphony-2,BloodBrother/symphony-2,DavidForster/symphony-2,twiro/symphony-2,DeuxHuitHuit/symphony-2,alexnantel88/symphony-2,twiro/symphony-2,mazedigital/jcilearn,jensscherbl/symphony,brendo/symphony-2,jensscherbl/symphony,michael-e/symphony-2,bauhouse/sym-todo-list,johnpuddephatt/symphony-2,johnpuddephatt/symphony-2,symphonycms/symphony-2,brendo/symphony-2