Moved code to src
	new file:   src/expr/Benchmark.java
	new file:   src/expr/Example.java
	new file:   src/expr/Expr.java
	new file:   src/expr/Parser.java
	new file:   src/expr/RegressionTest.java
	new file:   src/expr/Scanner.java
	new file:   src/expr/SyntaxException.java
	new file:   src/expr/Token.java
	new file:   src/expr/Variable.java
	deleted:    expr/Benchmark.java
	deleted:    expr/Example.java
	deleted:    expr/Expr.java
	deleted:    expr/Parser.java
	deleted:    expr/RegressionTest.java
	deleted:    expr/Scanner.java
	deleted:    expr/SyntaxException.java
	deleted:    expr/Token.java
	deleted:    expr/Variable.java