COFFEE: change autotuner's compile options
COFFEE: fix appending pragmas in non-mixed case
COFFEE: fix generation of BLAS when autotuning
COFFEE: restore tensor layout only if needed
COFFEE: make plan_cpu profilable
COFFEE: add debug functionalities to autotuner
COFFEE: initialize tmps if needed by zero-removal
COFFEE: change some variable names and comments
COFFEE: fix bug when merging loops