Additional commands

Adding reimplementations of various additional plan 9 tools. An attempt was
made to match behaviour (flags, output) as much as possible, but no peeking
in the source was done.

cat: concatenate files
cmp: compare files
comm: compare lines in sorted files
cp: copy files
echo: output arguments
freq: histogrammer
tee: clone input into separate files
uniq: search for duplicate lines in sorted files
wc: word/rune/byte/line count

Wc is the program that is most suspect as the algorithm is totally new. There are
differences in word count between Plan 9's wc, BSD's wc (OSX) and this command as it
There is a significant difference between "bad rune" counts in Plan 9's wc and this code
(BSD doesn't implement it). wc doesn't know about runes from 0x10000 to 0x10ffff.