Expressions

- Implemented sequence --> infix converter.
- Added new Lexer code.
- Added Lexer unit tests.

src/commands/CmdCustom.cpp

@@ -95,8 +95,6 @@ int CmdCustom::execute (std::string& output)
 ////////////////////////////////////
   Arguments f = context.args.extract_read_only_filter ();
   Expression e (f);
-  e.toInfix ();
-  e.toPostfix ();
 
 return 0;
   // TODO e.apply (tasks);