FORMUS3IC_LAS3 / embb

Added EMBB_UNUSED_IN_RELEASE macro in thread_specific_storage-inl.h to avoid warning about unused variable.

This reverts commit 807308ab819e778915b8a6c5c5cdb68288233f72.
This reverts commit 399ddba00be2f45a4768f4a2e92d1c12d3e75552.

4 spaces to get code blocks
Conflicts:
	README.md

- shift initialization of is_active to correct position
- remove unused variable

  (this probably works on MacOS too, but not tested yet)

While on it, fix error message. The missing include file
is not the root cause of the problem. The missing implementation
of embb_core_count_available() is.

HelpScan was implemented wrong -> Scan could be executed be different threads the same time -> FixedSize lists got messed up -> program tried to return wrong pointers to the object pool -> segfault or hang

Moreover, added assertion that checks that only one thread concurrently enters scan, for avoiding these kind of bugs in the future.

Fix internal issue #214, change default doxygen label for api to two (using javascript to collapse to that level)

- Omit doxygen "Makefiles" from tarball (internal issue #221)
- Add executable flag to shell scripts (fixes internal issue #224)