Create cave.rb

cave.rb started as a silly project tonight on the idea of creating a very simple and pseudo-procedurally-generated "cave exploration" game in Ruby.  The concept was effectively an old text-based adventure game where a player could explore an infinite cave of interlinking rooms.  There is no real purpose.

While currently untested, it serves as something of a demonstration of minimalist code and clever ways to manipulate objects and data in Ruby.  A feature not yet exploited (and which needs a condition test) is the bundling of binary data inside of the initial comment block -- thus allowing for the storage and shipping of "clutter" to be found and carried about the cave.

Perhaps my favorite bit of code (tied with the call for gen_room) is the mainloop itself, which defers function calls based on a Hash containing regular expressions of known "commands" mapped to their analogous function symbols.