Release 1.1.5 adds door bashing.  You need to have a 2h sword or axe equip to be able to bash a door.  How many swings it might take is dependent on your current strength.  This should provide a nice alternative to keys.

I didn't add it in this release, but in the next release I am going to add in some code to alert monsters when players perform a door bash.  It will be a random chance.  It should balance things out with key usage since keys do not alert monsters.

I'm going to go ahead and do the pick axe and digging for the next version too.  It will also alert monsters, and some walls may be unbreakable.  Though, it should be an interesting tool to have.  They will be fairly rare though since being able to dig out entire dungeon sections could make things a bit too easy.  They will also be prone to breakage.