Replaced .h C headers with c-prefixed version and added std:: prefix to C standard library usage (#90)

This was not done to stdint.h for brevity in type names. Also removed "using namespace std;".

wpilibc/sim/src/Timer.cpp

@@ -86,7 +86,7 @@ Timer::Timer() : m_startTime(0.0), m_accumulatedTime(0.0), m_running(false) {
  * start time stored in the timer class. If the clock is not running, then
  * return the time when it was last stopped.
  *
- * @return unsigned Current time value for this timer in seconds
+ * @return Current time value for this timer in seconds
  */
 double Timer::Get() const {
   double result;