Parse subset of the C# code to the Expression

This is the last missing step in library,

I have my AST in a form of Expression,
I can Compile or I can output a C# code from it
I may even output the expression as a C# code to create the same expression.
I can convert between LightExpression and Expression and vice versa.

Now, I think, I need to write a parser, and I will have the complete compiler independent of Roslyn.
This may be ideal for the small code-gen tasks.

**Update:**

Start from the small subset, e.g. from the Method calls. This way, I may start parsing the output of `ToExpressionString()`.
Ideally, at the end I should be able to parse output of the `ToCSharpString()`.