Added two tests for refinement between machines
Implemented the progressive propagation of modeling elements through the refinement structure.

It allows the use of inherited variables when parsing expressions.
Changed the visitor design to increase the flexibility of the kind of visitation rule that can be used.

Before, the rules looked like this
    Env1Args2Blocks $ \(a_string, a_raw_block, another_raw_block) state -> do ...

where Env1Args2Blocks is one case of an algebraic type. This means that there has to be one case for each for each possible list of arguments of LaTeX environmants and commands with a corresponding branch in the visitor algorithm. Now, all the possible argument lists are covered by one case for environments and for commands.

All the magic resides in Document.TypeList. It defines two classes: Readable and TypeList. Every type that can be parsed as the argument of an environment or a command must be an instance of Readable. It provides an action that convert a LaTeX parse tree into one argument of the proper type. TypeList provides a command that parses a tuple of Readable arguments.

Everything is statically typed.
Modified the continuous tester to improve the trigger. Testing is now triggered when, after compiling, the test binary is newer than last_result.txt
Shifted the duty of parsing labels, integers, sets (and lists) of labels to the visitor. Possible improvement: derive Readable from Read.
Started a LaTeX design document
changed the build system to trigger a compilation / testing phase when the time stamp of some of the source files change
Changed the schedule system so that every event has a set of schedule and a sequence of schedule refinement rules.

o \transient now take a schedule number as a second argument.
o it is now possible (and necessary) to use \weakento{evt}{3}{remove}{add} to introduce schedules to event that didn't use to have one
o it is now possible (but untested) to use \replace{evt}{3}{remove}{add}{keep}{prog}{saf} in order to replace parts of a schedule and prove the soundness using prog and saf, the leads-to property and the safety property that needs to be proved.