Remove autotools-generated files.
.gitignore: Add auto-generated files previously under version control.
configure.ac: Remove AC_SUBST(VERSION); unnecessary.
wmforecast.c: Use PACKAGE_STRING for --version; update to reflect GNU coding
standards (http://www.gnu.org/prep/standards/html_node/_002d_002dversion.html).
wmforecast.c: Print -help text when invalid command line option given.
wmforecast.c: Simplify --help output, add homepage.