libxmp release 4.7.1
add examples directory and BUILD.md CONTRIBUTING.md to `make dist'
docs/manpage.rst: update date.
Add BUILD.md, CONTRIBUTING.md, and a pull request template.
Enforce NUL terminator for BSP entity lump
flt_load.c: Remove use of addressof operator on an array
update changelog and copyright years of changed sources, so far.
Rewrite smix WAV loader and fix smix sample load/free bugs.