First commit of lv2

Simplifying stop in Node
Changing the language to have variable instead of simple aliases

The symbol table is now used, and the parent node has to be retrieve
Merge branch 'master' into languagev2
Added the ability to have list of variables in the language
Merge branch 'master' into languagev2
Adding the function Node to the language
Adding function and definition of Function

Also preparing to remove the interpreter from every node
Interpreter is only present in the NodeProgram

An Exception has been created
Added some stuff in the interpreter

Added exceptions
Added NodeReturn
Added NodeAssignationVariable
Merge branch 'master' into languagev2
Function return value
Merge branch 'master' into languagev2
Some doc and cleaning code
NodeSelect added

And some tests on the copy
Added NodeValue and NodeBinaryExpression to supplant the NodeSeqAndBool
Merge branch 'master' into languagev2
BinaryExpression replaces NodeSeqBool, NodeRelationBool and NodeExpBool
SeqAndRules does not exist anymore
Merge branch 'master' into languagev2
Added Events and correcting language

Simplifying it by removing some arrays