cut another syscall; avoid magic numbers

No need to bother the operating system to close the
file descriptor, because it will clean up after me.

Also, -1 is less readable than INDEX_INVALID.

lib: avoid propagating types needlessly

Just because a libc function returns unsigned long doesn't mean the
entire codebase has to use unsigned long. The numbers fit into 13 bits;
typecasting is OK.

lib: reduce number of syscalls

Nine is getting to a tolerable range.

get max brightness at compile time

Fourteen syscalls is too many for me.

gitignore .o files

lib: correct usage message

I deleted that option a while ago.

Use a more conventional integration technique

lib: update style to my current persuasion

lib: avoid writing function prototypes

Makefile: let valgrind return nonzero on error

don't use typedef

lib.c: remove unused "rep" feature

add LICENSE

rename notes -> README.md

lib.c: fix an OOB access introduced by -Os flag

This is not really fixing the place responsible for the error, just
routing around it, but I think it reads better, so I'm going with it.

Valgrind didn't catch this bug because the location of the OOB access
is a global static array. exp-sgcheck is supposed to check this, but
it didn't work for me.

Add new argument: number of repetitions

Move all bl.c logic into lib.c

auto: don't print so much

add .gitignore

Remove trailing space