Fix header guard for amalgamation
Have clear_mem just be a plain memset and only call the (slow)
zero_mem just before a deallocation where we are actually at risk of
the compiler eliding the writes.
Move mul and square operations on a elliptic curve to CurveGFp so we
can use different representations/operations depending on the curve
(eg, using a specialized version for P-256 reduction)
Asserts here are nice
Don't bother polling std:: clocks if we have clock_gettime
Fix decoding indefinite length BER constructs that contain a context
sensitive tag of zero. Github pull 26 from Janusz Chorko.