gcc, and recent clang-10 can construct new objects
using references as arguments.
However clang-8 (and MSVC?) do not:
"error: no matching function for call to 'operator new'"
The compiler apparently does not expand the template
class A <-> `A*` vs. `A const&`
for different cases.
This is a dumb stack allocator using LIFO allocation/free, with
a fallback to new/delete. This works well for small STL containers
in particular std::vector, but it's also suitable for std::map<>,
in particular copy constructing small POD maps (plugin pin mappings).
Eventually this could be combined with TLSF for a flexible
memory arena management. This is however not currently needed
for any the planned use-cases.
This code is ANSI C++98 compatible, and yet also works with
modern C++11, C++14
