Add trailing newline
Replace ABC_FUNC_C_CALLBACK with more generic ABC_STL_CALLCONV

Named ABC_STL_CALLCONV, the former ABC_FUNC_C_CALLBACK can be used in more
places, superseding local hacks in memory.{c,h}xx.
Remove unnecessary forward declarations
Fix braces style
Sort methods
Refactor index checking on abc::str_base_ and abc::vector_base operator[]

Consolidate the code from these two implementations into the new
_raw_vextr_impl_base::validate_index().

Also change the type of the argument of operator[] to intptr_t, to check
for negative indices in a clearer way than expecting the sign bit turned
into MSB to have made the index too big. You didn’t get that? Exactly.
Use char ** instead of abc::char_t ** for argv
Initial support for the new testing framework
Don’t use CL() on template parameter-typed character literals
Rename assert() macro to ABC_ASSERT()

It’s a macro, so its name should be all-upper-case. Also, new code wants
to use the “assert” identifier, so it can’t be a macro.
Add testing unit for new testing framework
Add test runner class

Move (future) functionality from abc::testing::module to
abc::testing::runner.
Add test result logging support
Support automatic instantiation of registered units

abc::testing::unit-derived classes using ABC_TESTING_UNIT_REGISTER() (in
any source file) now will be loaded automatically when a runner is
instantiated by abc::testing::module.
Fix printing of stack trace on uncaught exceptions
Actually execute instantiated testing units
Automatically execute the test binary when the "test" make target is generated
Replace usage of abc::_scope_trace<> with abc::_scope_trace_impl
Rename abc::exception::_uncaught_exception_end() to write_with_scope_trace()

Make this static method more generic by making it able to write on any
stream, not just stderr; accordingly, rename it to reflect its broader
usage.
Sort abc::exception methods