Revert "Ingres-specific SQL changes done."

This reverts commit ad01a3d873a164af8624775b34366769342dcf54.
Revert "Renamed the compilation units."

This reverts commit 821a9b388fc2b2bcdf657d5240998cf9912e410d.
Revert "Renamed the compilation units. Also cloned the main resources from PostgreSQL to Ingres."

This reverts commit b32d7ff570a2afe655c6bb68be7b854586803e85.
Revert "Forked the PostgreSQL to Ingres."

This reverts commit e14e01951f303b12b7a721fb873182b1aea43c36.
Revert "Added Ingres dependencies."

This reverts commit 9aa41bc56c7b52682d9388e34697078eac8a43fd.
Revert "Fixed Maven and Ant paths to work in a typical Linux system out of the box."

This reverts commit e3d9356e92b1ed7cd64940fbe911670e25d85510.