Add isZero to LF.
Overhaul linear expressions and conditions parsers.
Add Mockito support in the SBT definition.
Add support for numeric expressions and assignments.
Add parser for numeric expressions.
Rename LinearExpressionParser into LinearFormParser.
Make LinearFormParser generate a LinearForm over doubles instead of ints.

Doubles are more general than ints, therefore it is a better temporary
solution until a proper handling of numeric types is implemented.
Convert targets to use NumericExpression.
Remove LinearAssignment class.

It is completely subsumed by NumericAssignment (which is itself not very
useful).
Correctly print variable names in LTS target.
Add support for regions into LTS target.
Rename LinearCond into NumericCondition.

Also remove linearcondition package.
Add a target class for multiple assignments.
Add in LTS support for multiple assignments.
Add Faster support for LTS.