add m4 highlighting
add m4 highlighting

BUG: 280174

jfmcarreira/kate,cmacq2/kate,cmacq2/kate,sandsmark/kate,DickJ/kate,cmacq2/kate,DickJ/kate,DickJ/kate,hlamer/kate,hlamer/kate,hlamer/kate,DickJ/kate,hlamer/kate,hlamer/kate,hlamer/kate,hlamer/kate,jfmcarreira/kate,hlamer/kate,sandsmark/kate,hlamer/kate,jfmcarreira/kate,sandsmark/kate,sandsmark/kate,hlamer/kate