Add function to update alignment

[javagl]

Addresses #134 :

This adds a command updateAlignment that can be applied to B3DM, I3DM, PNTS, and CMPT files, and just ensures that the elignment requirements for the batch- and feature table and the tile data as a whole are met.

I tested it with an old version of the CesiumJS spec data (the one before this commit), and it fixed most of the validation errors from that state. (Adding a spec could make sense, but ... creating the "invalid" data would take most of the time here...). In any case, the README.md still has to be updated.

[javagl]

I added specs based on the "old" CesiumJS specs data (one B3DM, I3DM, PNTS, and CMPT). They all caused validation errors before. The specs are comparing the result of running updateAlignment to the versions that are contained in the golden subdirectory, which no longer cause validation errors.

The README.md has been updated to include the updateAlignment command.

(An aside: One could make a case for adding this "alignment update" as part of the upgrade command. Technically, this would be trivial. But some details might have to be sorted out in terms of the desired configurability (even though the update options are not exposed right now beyond the targetVersion anyhow). Cases where someone wants to fix the alignment of a B3DM without upgrading its glTF 1.0 to 2.0, or someone wants to fix the alignment for B3DM and not for PNTS are unlikely, so it might just be part of the detault targetVersion=1.0 update...)