Refactoring: Expression
Added: Constant, Variable (type of Expression)
Refactoring: Expression
Added: Constant, Variable (type of Expression)
Merge pull request #1 from aivel/max

Refactoring: Expression
qq
Merge remote-tracking branch 'origin/max' into sem

Conflicts:
	src/com/danilov/bool4j/test/MainTest.java
	src/ru/matlog/bool4j/expression/Expression.java
	src/ru/matlog/bool4j/expression/function/Functions.java
	src/ru/matlog/bool4j/expression/operator/Operators.java