Improved Makefile.

[alissa-huskey]

I initially created this fork becaus when I ran make install the VERSION variable was not updated in todo.sh. So todo -V would produce:

TODO.TXT Command Line Interface v@DEV_VERSION@
...

But now I can't reproduce the problem. Shrug.

So instead: Here's a nicer Makefile if you want it!

Usage features:

• Separate make build command that creates and populates the todo.txt_cli-*/ directory (and is in turn called by make dist.
• A new make help command that lists all public targets.

Implementation changes:

• VERSION-FILE is no longer generated every time make is run, only when required (by build/dist/clean etc, but test).
• Refactored the dist target into separate file targets which is more atomic and make idiomatic. This may or may not be desirable as some people might find it confusing.
• I added a bunch of missing .PHONY declarations.
• Added lots of comments.

You can verify that the dist files are still generated correctly with the following:

mkdir -p tmp && cd tmp
git clone git@github.com:todotxt/todo.txt-cli.git todo
git clone --branch makefile git@github.com:alissa-huskey/todo.txt-cli.git todo-fork
mkdir dist dist-fork
make -C todo dist && make -C todo-fork dist
tar xzvf todo/*.tar.gz --directory ./dist && tar xzvf todo-fork/*.tar.gz --directory dist-fork

# confirm they contain the same files
diff <(ls dist/todo*/) <(ls dist-fork/todo*/)

# confirm the contents of all files are the same
for f in dist/todo*/*; do diff -w ${f} dist-fork/todo*/${f##*/} ; done

Hope you find it useful!