add support to del
support envdel
bugs: word boundary to envdel, no escape quote

1) envdel g deleted all character g from variable
2) Bash does not need escaping of '"' in, e.g.
   a ${} closure. We don't want to parse bash so
   we'll just avoid escaping altogether.
3) envdel should not keep space at the end of the
   string. For example envdel g of "X g" should
   result "X" and not "X ".
print environment file's source
.gitignore output binaries + vim's *.swp