redis-benchmark: update help for new __rand_int__ form.
SCAN: tests moved to unit/scan.tcl.
SCAN test keys sorting turned into more idiomatic Tcl.
Test: added SSCAN test.
Test: added HSCAN test.
Test: added ZSCAN test.
Test: added a SCAN test trying to trigger HT resize.
Regression test added for [SHZ]SCAN issue #1354.
scanGenericCommand() refactoring and handling of integer encoded elements.

This commit fixes issue #1354.
Inverted variable boolean value and name after scanGenericCommand() refactoring.
SSCAN with integer encoded object test improved.