Core update -- use zero upper only in horizontal operations, but not in exp-avx because it leads to bug in GCC (where some registers are not saved and so are erased)

Update cmake and doc - update the detection of Inastemp included by another project and put the cmake options in the readme

Add GEMM example - might be improved in the future but already provide 40/20 GFlop-s in float/double

Update exponential - use const expr instead of array for coef and write factor computation in a single line

Add a test in the cmakelist to remove warnings when inastemp is not included by another cmake project (message was: current scope has no parent).