[aur-general] Merge requests: mpich2 -> mpich

With the release of MPICH 3.0, the project name has been changed from MPICH2 to MPICH. (It is still backward-compatible.) I have updated my packages accordingly, which includes a directory change from /opt/mpich2/ to /opt/mpich/. Could you please merge the following packages? mpich2 -> mpich https://aur.archlinux.org/packages/mpich2/ https://aur.archlinux.org/packages/mpich/ parmetis-mpich2 -> parmetis-mpich https://aur.archlinux.org/packages/parmetis-mpich2/ https://aur.archlinux.org/packages/parmetis-mpich/ ptscotch-mpich2 -> ptscotch-mpich https://aur.archlinux.org/packages/ptscotch-mpich2/ https://aur.archlinux.org/packages/ptscotch-mpich/