Additional include.
Prevent warnings about the inclusion order.
Add AM_CPPFLAGS to facilitate out of source builds.
Merge pull request #4 from blattms/master

Facilitate out of source builds and remove some warnings
Changed OpenRS->OPM in copyright notices and #include guards
Merge pull request #6 from totto82/openRStoOPM

Changed OpenRS->OPM in copyright notices and #include guards