* U.S. special forces failed to capture Ikrima on Saturday
* Ikrima seen as an "external operations" planner
* He was a protege of leading al Qaeda operatives
* Kenyan intelligence says masterminded several plots
By Richard Lough
NAIROBI, Oct 8 (Reuters) - Ikrima, the militant targeted by U.S. special forces in a failed weekend raid, is a Somali-based thinker, planner and ...