Single modification: update to EPTCS style

• Export script can now produce a flat zip file
• A shell script can produce a "diff" document (with the help of latexdiff)
• Update to ACM journal class

Single modification: update of Springer LNCS stylesheet to latest version (2.21).

• Updated ACM conference style to latest version
• Old Springer journal style replaced with the new Springer Nature classes
• Updated Makefile to version 2.2.1

• Update to LIPICS style using the 2021 class file (formerly was 2016)
• The export script now includes LabPal files if any
• authors.txt can now include (optionally) the e-mail and ORCID of each author (although only LIPICS currently uses this info)

Novelties in this version:

• Support for IEEE Transactions (CompSoc)
• Better support for ACM conference templates
• Support for IEEE Computer Society magazines
• Files ending in -amble.inc.tex are now versioned by default

Sorry for the version number jump!

• Updated IEEE class to latest version (1.8b)
• Bugfix to generation of authors in IEEE stylesheets
• Switch to support either IEEE conference or journal style

Added support for USENIX papers