LG Half Block connectors were using wrong construction models

Sorry for two updates in same day.

Added Large Grid Half Block Connector
Added 3 Large Grid 'Small Connector' Blocks which work with the new 'Small Connector' for SG
Reworked UV mapping on most blocks to work better with certain skins
Fixed issue with LG 2x1 decal using incorrect texture
Rebuilt SG 3x3x1 Connector, Conveyor Connector, and Collector models so they look less squished
Small increase to construction costs of conveyor connectors
Increase construction cost of Mega Connector to be more in line with others
Removed stage 3 construction models from some SG blocks, seriously they showed for a millisecond, not needed