[td-98] fix bugs while query/insert mixed up in sql requests.

add const in API

fix duplicate commit key

Feature/query

check null pointer in tscSql.c.

add test

Feature/vpeer

fix print typo in general/db/basic5.sim.

turn on the arbitrator code

refCount may be negative if vnodeRelease is called appropriately

make output clear and add general/db testcases.

add assert there in case it happens

Feature/sync

Feature/balance

fix stop_dnodes.sh with postpone socket cleanup and same timestamp is…