Support for deleting files

Basic support for the command rm has been added.  Should function a-okay
Fixed fat32_writedir

fat32_writedir relied on the directory table, which is now deprecated.  All references will be removed in a later revision
Added 'Command Not Found' error message to shell'
Removed unnecessary printlines
New shell command in writes a word to a file

Basic support for writing (no append) to files has been added
Fixed logic bug in writing multiple clusters

When more data was being written than one cluster could contain, the cluster offset was never being reset.  Thus it would start writing in the middle of a cluster instead of at the beginning.
Updates to fat32_writedata

Now supports opening files with the append option.  Plus numerous other small bug fixes