* NEWS, doc/tl/tl.tex, doc/tl/tl.bib: Document these new operators.
* spot/parsetl/parsetl.yy, spot/parsetl/scantl.ll: Parse those.
* spot/tl/formula.cc, spot/tl/formula.hh: Add constructors.
* spot/gen/formulas.cc: Use it.
* tests/core/sugar.test: New file.
* tests/Makefile.am: Add it.
