Add pencil-util information to the README.

Change-Id: I1d91959432dc6c93764288fa0bf1cf4a388bbe42
Link with math library in testsuite.

Change-Id: I5a6fd7d0217e7cc54c8947a1df9500bfe0d57268
Check for static function in forward declarations.

static void foo();

voif foo(){}

is forbidden now.

Change-Id: Id172b30cadf409e608eafa2615bde13466a226a6