Addresses some of the open issues

* Fixes issue #26 by explicitly initializing the members of struct Unity Unity, leaving .AbortFrame deliberately uninitialized.
* Avoids identifiers starting with an underscore and a capital letter as these are always reserved for any use (C99/11 7.1.3p1).
* Safety check for guarded malloc.
* Delays inclusion of &lt;string.h&gt;, because this header includes <stdlib.h> on glibc, which would cause undefined behaviour due to the redefinition of malloc() and friends.
* some minor tweaks