improve error reporting, other refactoring
Re-enable document dump

Once again, 'jeolm build --dump' will create a standalone LaTeX
document.
refactoring in records.py
Massive refactoring of driver
Factor out argparser.py
Move most 'main' code to commands.py
High-level refactoring

MetadataManager, Builder and FilesystemManager are now less dependent on
each other.
Add buildline.py, along with massive refactoring

and some fixes.
Remove argparser.py as a result of refactoring
Refactor diffprint.py and fancify.py

Along with minor refactoring in spell.py and some other fixes.