* Al Qaeda accused of orchestrating the attacks
* Violence last year the worst since 2006-07 peak
* Sunnis feel sidelined since majority Shi'ite rule began in 2003 (Adds Sadr speech)
By Ahmed Rasheed and Ali al-Rubaie
BAGHDAD/HILLA, Iraq, Feb 18 (Reuters) - Bombs exploded in predominantly Shi'ite Muslim districts of the Iraqi capital and in the southern city of Hilla on Tuesday, killing...