#63 smarter definition of "word"

[Oswald Buddenhagen]

this applies to both navigation by and deletion of words.
currently everything from a certain set of characters is a
word, everything else is a delimiter.
there are two levels of improvement:
- special chars become a second category of words.
each word category is a delimiter for the other one, just
like whitespace is. mcedit does this and it is already
pretty useful.
- instead of doing simple ascii classification, define
words to be language- & context-specific tokens. that
would be cool, but the effort is beyond reason. well,
maybe integrating it into syntax highlighting would make
it manageable.