Adds two executable shell scripts, rl and rlmk

Install with

make install

rl searches the current and all parent directories for an rl.sh file. If it finds one, it will source it then run the arguments to rl as a command. This lets you easily use for example libraries and executables within the project without installing anything. Add an rl.sh file at the root directory of the project. To run commands within this local context, do

rl <COMMAND>

from anywhere within the project. While processing rl.sh, the RL_ROOT variable will be defined as the directory that rl.sh lives in.

mkdir -p bin child_dir
echo '#!/usr/bin/env sh\necho Hello World!' > bin/example
chmod u+x bin/example
echo 'export PATH=$RL_ROOT/bin:$PATH' > rl.sh
cd child_dir
rl example

The script bin/example is found and executed on the last line, even from some other directory, because rl.sh adds it to the PATH.

rlmk is a shortcut to run make in the same directory as the rl.sh found by rl. Extra arguments are passed through to the make invocation. This may be useful to quickly run PHONY targets from anywhere in the project tree.

rlmk doesn't automatically include the enviroment set up by rl. This is a deliberate design choice to discourage unintentially writing Makefiles that only work when run with rl. To run the Makefile with the rl enviroment, either run rl as needed within the Makefile or prefix the rlmk invocation with rl as you would with other commands:

rl rlmk <MAKE TARGET>