Finer dependency tracking

now touch lib/assemble.ml && make doesn't rebuild everything (which is quite expected ...)
Revert "Finer dependency tracking"

This reverts commit 4f0c0dfff9be02eac84bb865d630b6d5ba9c3314.
Better fix for finer dependencies
Merge pull request #70 from samoht/better-deps

Finer dependency tracking