* spot/tl/formula.cc, spot/tl/formula.hh (formula::sugar_delay): New
function to implement this operator as syntactic sugar.
* spot/parsetl/parsetl.yy, spot/parsetl/scantl.ll: Parse it.
* doc/tl/tl.tex: Document the syntactic sugar rules and precedence.
* tests/core/sugar.test: Add tests.
* NEWS: Mention this new feature.