Rearrange DTK_x constants. Define constants to allow day of week decoding. Add new datetime and timespan routines.
Rearrange DTK_x constants.
Define constants to allow day of week decoding.
Add new datetime and timespan routines.

xinzweb/gpdb,rvs/gpdb,postmind-net/postgres-xl,chrishajas/gpdb,techdragon/Postgres-XL,adam8157/gpdb,Postgres-XL/Postgres-XL,jmcatamney/gpdb,zeroae/postgres-xl,edespino/gpdb,randomtask1155/gpdb,lisakowen/gpdb,janebeckman/gpdb,yuanzhao/gpdb,yuanzhao/gpdb,lisakowen/gpdb,ahachete/gpdb,xuegang/gpdb,xuegang/gpdb,yuanzhao/gpdb,zaksoup/gpdb,atris/gpdb,ashwinstar/gpdb,royc1/gpdb,rvs/gpdb,lisakowen/gpdb,cjcjameson/gpdb,edespino/gpdb,arcivanov/postgres-xl,50wu/gpdb,Postgres-XL/Postgres-XL,lpetrov-pivotal/gpdb,jmcatamney/gpdb,ahachete/gpdb,tangp3/gpdb,CraigHarris/gpdb,CraigHarris/gpdb,zaksoup/gpdb,tangp3/gpdb,rvs/gpdb,ashwinstar/gpdb,cjcjameson/gpdb,pavanvd/postgres-xl,cjcjameson/gpdb,lintzc/gpdb,xuegang/gpdb,foyzur/gpdb,tpostgres-projects/tPostgres,kmjungersen/PostgresXL,lintzc/gpdb,rvs/gpdb,kmjungersen/PostgresXL,Quikling/gpdb,Chibin/gpdb,yazun/postgres-xl,xinzweb/gpdb,foyzur/gpdb,greenplum-db/gpdb,xuegang/gpdb,randomtask1155/gpdb,kaknikhil/gpdb,snaga/postgres-xl,edespino/gpdb,Postgres-XL/Postgres-XL,randomtask1155/gpdb,CraigHarris/gpdb,0x0FFF/gpdb,Chibin/gpdb,50wu/gpdb,lpetrov-pivotal/gpdb,arcivanov/postgres-xl,tpostgres-projects/tPostgres,pavanvd/postgres-xl,Chibin/gpdb,Quikling/gpdb,foyzur/gpdb,ashwinstar/gpdb,yuanzhao/gpdb,edespino/gpdb,postmind-net/postgres-xl,janebeckman/gpdb,kaknikhil/gpdb,royc1/gpdb,pavanvd/postgres-xl,rvs/gpdb,zeroae/postgres-xl,CraigHarris/gpdb,yazun/postgres-xl,postmind-net/postgres-xl,Quikling/gpdb,ovr/postgres-xl,arcivanov/postgres-xl,cjcjameson/gpdb,kaknikhil/gpdb,edespino/gpdb,Quikling/gpdb,randomtask1155/gpdb,janebeckman/gpdb,yuanzhao/gpdb,yuanzhao/gpdb,royc1/gpdb,edespino/gpdb,rubikloud/gpdb,edespino/gpdb,kaknikhil/gpdb,pavanvd/postgres-xl,lpetrov-pivotal/gpdb,chrishajas/gpdb,randomtask1155/gpdb,lpetrov-pivotal/gpdb,cjcjameson/gpdb,lisakowen/gpdb,edespino/gpdb,atris/gpdb,CraigHarris/gpdb,atris/gpdb,xinzweb/gpdb,postmind-net/postgres-xl,50wu/gpdb,greenplum-db/gpdb,tangp3/gpdb,Chibin/gpdb,ahachete/gpdb,ahachete/gpdb,lpetrov-pivotal/gpdb,xinzweb/gpdb,zaksoup/gpdb,janebeckman/gpdb,snaga/postgres-xl,50wu/gpdb,adam8157/gpdb,atris/gpdb,ashwinstar/gpdb,yuanzhao/gpdb,adam8157/gpdb,royc1/gpdb,0x0FFF/gpdb,lisakowen/gpdb,kmjungersen/PostgresXL,kaknikhil/gpdb,Quikling/gpdb,rubikloud/gpdb,tangp3/gpdb,rubikloud/gpdb,zeroae/postgres-xl,jmcatamney/gpdb,kmjungersen/PostgresXL,lisakowen/gpdb,xinzweb/gpdb,greenplum-db/gpdb,rubikloud/gpdb,oberstet/postgres-xl,janebeckman/gpdb,royc1/gpdb,zaksoup/gpdb,lintzc/gpdb,foyzur/gpdb,lintzc/gpdb,xuegang/gpdb,tangp3/gpdb,zaksoup/gpdb,rubikloud/gpdb,yazun/postgres-xl,lpetrov-pivotal/gpdb,lisakowen/gpdb,50wu/gpdb,greenplum-db/gpdb,atris/gpdb,randomtask1155/gpdb,greenplum-db/gpdb,Chibin/gpdb,yazun/postgres-xl,ovr/postgres-xl,edespino/gpdb,oberstet/postgres-xl,ashwinstar/gpdb,chrishajas/gpdb,Postgres-XL/Postgres-XL,janebeckman/gpdb,foyzur/gpdb,jmcatamney/gpdb,adam8157/gpdb,tangp3/gpdb,jmcatamney/gpdb,foyzur/gpdb,ahachete/gpdb,adam8157/gpdb,xinzweb/gpdb,CraigHarris/gpdb,tpostgres-projects/tPostgres,yuanzhao/gpdb,ahachete/gpdb,0x0FFF/gpdb,kaknikhil/gpdb,tangp3/gpdb,adam8157/gpdb,tpostgres-projects/tPostgres,Quikling/gpdb,snaga/postgres-xl,chrishajas/gpdb,jmcatamney/gpdb,ovr/postgres-xl,greenplum-db/gpdb,atris/gpdb,rvs/gpdb,cjcjameson/gpdb,royc1/gpdb,rvs/gpdb,Chibin/gpdb,zeroae/postgres-xl,cjcjameson/gpdb,Chibin/gpdb,atris/gpdb,0x0FFF/gpdb,yazun/postgres-xl,arcivanov/postgres-xl,xuegang/gpdb,kmjungersen/PostgresXL,50wu/gpdb,yuanzhao/gpdb,rvs/gpdb,edespino/gpdb,cjcjameson/gpdb,Quikling/gpdb,xinzweb/gpdb,ashwinstar/gpdb,tpostgres-projects/tPostgres,CraigHarris/gpdb,kaknikhil/gpdb,ovr/postgres-xl,Chibin/gpdb,0x0FFF/gpdb,Chibin/gpdb,lpetrov-pivotal/gpdb,Quikling/gpdb,techdragon/Postgres-XL,rubikloud/gpdb,0x0FFF/gpdb,cjcjameson/gpdb,techdragon/Postgres-XL,zeroae/postgres-xl,Chibin/gpdb,janebeckman/gpdb,lisakowen/gpdb,postmind-net/postgres-xl,Quikling/gpdb,50wu/gpdb,CraigHarris/gpdb,arcivanov/postgres-xl,greenplum-db/gpdb,0x0FFF/gpdb,chrishajas/gpdb,janebeckman/gpdb,tangp3/gpdb,adam8157/gpdb,oberstet/postgres-xl,Postgres-XL/Postgres-XL,kaknikhil/gpdb,xuegang/gpdb,foyzur/gpdb,rubikloud/gpdb,lintzc/gpdb,xuegang/gpdb,zaksoup/gpdb,royc1/gpdb,oberstet/postgres-xl,jmcatamney/gpdb,chrishajas/gpdb,CraigHarris/gpdb,lintzc/gpdb,royc1/gpdb,xinzweb/gpdb,ashwinstar/gpdb,lpetrov-pivotal/gpdb,ahachete/gpdb,snaga/postgres-xl,kaknikhil/gpdb,rvs/gpdb,pavanvd/postgres-xl,cjcjameson/gpdb,ovr/postgres-xl,randomtask1155/gpdb,greenplum-db/gpdb,yuanzhao/gpdb,randomtask1155/gpdb,rubikloud/gpdb,chrishajas/gpdb,chrishajas/gpdb,janebeckman/gpdb,0x0FFF/gpdb,kaknikhil/gpdb,adam8157/gpdb,arcivanov/postgres-xl,lintzc/gpdb,50wu/gpdb,atris/gpdb,zaksoup/gpdb,janebeckman/gpdb,lintzc/gpdb,ahachete/gpdb,jmcatamney/gpdb,techdragon/Postgres-XL,ashwinstar/gpdb,rvs/gpdb,snaga/postgres-xl,xuegang/gpdb,oberstet/postgres-xl,zaksoup/gpdb,foyzur/gpdb,lintzc/gpdb,Quikling/gpdb,techdragon/Postgres-XL