Most of the *Free() functions are pretty generic so add macros to make creating them as easy as possible.
Create a distinction between *Free() functions that the caller uses to free memory and callbacks that free third-party resources. There are a number of cases where a driver needs to free resources but does not need a normal *Free() because it is handled by the interface.
Add common/object.h for macros that make object maintenance easier. This pattern can also be used for many more object functions.
The function pointer casting used when creating drivers made changing interfaces difficult and led to slightly divergent driver implementations. Unit testing caught production-level errors but there were a lot of small issues and the process was harder than it should have been.
Use void pointers instead so that no casts are required. Introduce the THIS_VOID and THIS() macros to make dealing with void pointers a little safer.
Since we don't want to expose void pointers in header files, driver functions have been removed from the headers and the various driver objects return their interface type. This cuts down on accessor methods and the vast majority of those functions were not being used. Move functions that are still required to .intern.h.
Remove the special "C" crypto functions that were used in libc and instead use the standard interface.
Add bufDup() and bufNewUsedC().
Arrange bufNewC() params to match bufNewUsedC() since they have always seemed backward.
Fix bufHex() to only render the used portion of the buffer and fix some places where used was not being set correctly.
Use a union to make macro assignments for all legal values without casting. This is much more likely to catch bad assignments.
These are more efficient than creating buffers in place when needed.
After replacement discovered that bufNewStr() and BufNewZ() were not being used in the core code so removed them. This required using the macros in tests which is not the usual pattern.
Add production checks to ensure no filter gets a zero-size input buffer.
Also, optimize the case where a filter returns no output. There's no sense in running downstream filters if they have no new input.
