Reworking tags and transformations, stage 3:
- everything is converted to the new shiny way of doing things. Well, everything except Gappa, which seems very unifinished anyway, and Encoding_instantiate, which is too complex and would like to update it with François. Also, I commented a little piece of exception reporting in manager/, will see it with Claude. THIS IS STILL A WORK IN PROGRESS! Please inform me about any bugs, ugly APIs, and proposed corrections. All the non-implemented things, mentioned in the previous commit message are still in the TODO list and will be done soon.