List of clients is now an array, not a linked list.

Increases access time.

Crashes.
Fix several arithmetical mistakes that caused crashes.

Setting sel to a negative value, realloc()ing with the wrong unit size,
focusing a client when there was none, dividing by zero when tile()ing,
etc.

Should work now, I'll merge it into master.
Merge branch 'index'.

The clients are no longer accessed through a linked list (that caused a
*lot* of for loops), but in a dynamically allocated array. This should
increase access time, simplify the code, and increase readability.
Attempt to start a more sophisticated terminal.

Before launching xterm, xinitrc will first search the system for a
terminal that supports creation of new windows through Ctrl+N (or
another simple key). This allows easier creation of new clients to test
stwm.

If no other terminal is found, it defaults to xterm.
Add quit().

Also add restart(), but it does not work correctly: clients are lost and
remain as ghosts.