Created NewLinkData and replaced references to the original LinkData.
Moved it to the mod_pocketDim.core package. Added Point4D, an immutable
point type for 3D integer coordinates with an added dimension ID.
Moved all configuration variables from mod_pocketDim to DDProperties
(formerly DimDoorsConfig). Changed property names to be clearer in
config file, modified some comments, and generally cleaned up the config
file. Fixed some missing properties and variables that were reading from
the wrong properties. Modified the order in which mod_pocketDim
instantiated some of its static fields so that they would load after
properties are read. Almost all classes load after properties are read.
Fixed indentation across various files and replaced references to
properties in mod_pocketDim with references to DDProperties.
