Skeleton of the new rules structure
Switch actions from delegates to expressions
More refactoring of actions
Intermediate commit with rules structure change
Updated copyright notice
Code refactoring

- Replace switches on element type with a discriminated union match
- Refactor pattern handling in rule definition
Fix tests
Fix test names
Rename rule-related classes
Rework rule activation process
Nested rule builders
Code refactoring
Split rule definition and compiled rule
First cut at rewriting action expressions
Use ExpressionVisitor from .NET 4 framework
Multiple conditions

Support multiple conditions for aggregates and existential elements
Code refactoring
Manage symbol scope automatically
Split alpha and beta conditions
Reworked construction of beta conditions