map_file

mapping map_file(string file)

Takes a filename, reads in the file, creates and returns a mapping in 
the following manner:

suppose the file is composed of the lines:
frog This is a frog
fish This is not a frog

The mapping returned would have keys "frog" and "fish".  
map["frog"]  would be "This is a frog".

Also, if the data after the key in the file is numeric, it will properly
convert the data to be numeric.
