Improvements include
* adding additional build flags that warn about stack-smashing
and type conversion errors
* run-time checks for valid function input values and adquate
space for the result of arithmetic operations.
* make sure default case for switch statements do something
besides just assert
* disable using env. var. debugging in release mode
Change-Id: I5f048310c5c56e05d9ec31bcc273404d6a0dd646
Chris Freehill