Non-deterministic template order

There's a problem with the way template files are picked. I use a
convention of naming backup or old copies of files with a trailing
minus. I found that in some cases, "index.html-" was being preferred
over "index.html".

The documentation says:

    looks for the files matching hello.* in the template root and picks
    the first matching file.

It would be a good idea to document what that order is (probably
lexical).

This is implemented using glob.glob(path_prefix + '.*'); glob() is
implemented with os.listdir() which is defined to return a list "in
arbitrary order."

Some quick examples using the -f (unsorted) flag with ls on a FreeBSD
box:

    # unsorted
    hot 53 % ls -lf | grep html
    -rw-r--r-- 1 leres wheel 0 Sep 8 15:49 x.html
    -rw-r--r-- 1 leres wheel 0 Sep 8 15:49 i.html
    -rw-r--r-- 1 leres wheel 0 Sep 8 15:49 i.html-

    hot 54 % rm x.html i.html-
    hot 55 % touch i.html-
    hot 56 % touch x.html

    # unsorted
    hot 57 % ls -lf | grep html
    -rw-r--r-- 1 leres wheel 0 Sep 8 15:50 x.html
    -rw-r--r-- 1 leres wheel 0 Sep 8 15:50 i.html-
    -rw-r--r-- 1 leres wheel 0 Sep 8 15:49 i.html

Indeed the unsorted order is arbitrary!

BTW, when you fix this, you might consider removing the check for
backup files:

    if not f.endswith('~')] # skip backup files

since they'll sort after all other printable characters.

                Craig