Bug 993286 - Patch 1/3: Get call setup state from call array, r=echou, a=1.4+
Bug 993286 - Patch 2/3: Support AT+CHLD=3 to merge calls, r=echou, a=1.4+
Bug 993286 - Patch 3/3: Add Call.Set() function, r=echou, a=1.4+