Update BuildRequires to enchant2
    
    The runtime requirement was switched to enchant2 a while ago, but the
    BuildRequires was missed.  The -devel package is no longer required to
    build though since no binding is built; the library is loaded through
    ctypes.
    
    Also, check imports as a minimal test (since the testsuite is not
    included in the upstream tarball), and update the project URL.