Update build.xml

Jars are no longer necessary.  Forge self-downloads.
Fix some NPEs on TileEngine when it has not be initialized
Redudent null check on instanceof
Merge pull request #508 from nevercast/fix-npe-engine

Fix some NPEs on TileEngine when it has not be initialized
Liquid Packets should not send before chunks on client join
Liquid Pipes do a full update periodically for client sync
Added config option in BuildCraftCore regarding long update period
Added to core as it may be used for other things in future too
Merge pull request #509 from nevercast/bug-pipe-sync

Better Liquid Pipe Client Syncronization
Updated mcmod.info
Fixed typo.
Repackage for new Forge.
Refactor/cleanup.
Initial 1.4.6 port.
Fixed NPE when no recommended version is found.
Add way to query for refinery recipes
Merge pull request #518 from narc0tiq/refinery-recipe-query2

API change: query for refinery recipes, now with Collections.unmodifiableSortedSet
Changes for 3.3.0 build.
Update build.xml for MC 1.4.6

Just changed the version numbers to ensure that the correct version of forge and MCP are downloaded
Pipes replace blocks like grass, vines, etc.
Pipe place sound.
Merge pull request #523 from tcooc/patch-itempipe

ItemPipe placing changes
Override shouldRefresh.