Corun

add corun design code
I add 3 variableds in SPARQLQuery class, that is: corun_running, corun_enabled, pattern_size corun change current execution codes. If you don't care specific execution method, you only need to take care of not forgetting assigning these variabled when create a new query.
If changes possibly affecting your codes, you can look execute_sparql_query part in core/engine/sparql.hpp.
Corun codes may bring bugs in other people' s codes. This very likely caused by different renewing timing of row_num and col_num .