Extend runtime2 to N-bit booleans and integers (1 <= N <= 64)

Allow runtime2 to read and write N-bit booleans and integers where N is an explicit length from 1 to 64 bits.  Add C-language unit tests for easier debugging of N-bit-long numbers (requires Criterion test framework with MIT license, https://github.com/Snaipe/Criterion, but never used by or deployed with Daffodil itself so no need to change Daffodil's LICENSE or NOTICE files).  Fix issue overwriting C fields when initializing ERDs and fields of C structures containing choices within choices.  Reduce differences between runtime1 and runtime2 when printing float numbers in XML infosets.