Add meson build system support

[xiota]

Tested on Arch Linux with Meson 1.4.1. Closes #278.

[xiota]

I tried to keep changes minimal... if desired, can also change the following:

• Add build/ to .gitignore. This is a commonly used build directory.
• Add a Makefile wrapper to run meson commands. This would not interfere with existing makefiles, but may be confusing for some users.

Depending on preference, may want to change following:

• Remove prefix=/usr. (Default is /usr/local.)

Future changes to consider:

• Update existing build scripts to use buildDateTime.h.in