* remove superfluous semicolon
* Remove C-style casts from public headers
clang warns about them with -Wold-style-cast. It also warns about
implicitly casting away const with -Wcast-qual. Fix both by removing
unnecessary casts and converting the remaining ones to C++ casts.
They seemed to produce a hang when running self tests in AppVeyor.
Also use IsDebuggerPresent() to determine when we should call DebugBreak(). The OS killed our debug build when fuzzing caused an assert to fail
In release builds replace assert with void instruction `(void)0`. Otherwise in some places you will end up with statements like `if (...) ;` and some compiler will complain about it.
This avoids a circular dependency between misc.h and trap.h. It also allows us to logically segregate and group code to replace C++ handlers, like set_terminate
trap.h and CRYPTOPP_ASSERT has existed for over a year in Master. We deferred on the cut-over waiting for a minor version bump (5.7). We have to use it now due to CVE-2016-7420
