Fix #57 (LHS var name shadow of RHS expr fails to compile)

[pierrec]

Fix #57

[nalgeon]

Honestly, I don't like this change. It makes the transpiler logic more complicated for a use case that, in my opinion, shouldn't be encouraged in the first place — shadowing the variable in the assignment like this:

p := person{age: 42}
{
	p := p.age + 1
}

[pierrec]

Fair enough. Maybe then provide a So compiler error instead?

[nalgeon]

Great idea! Added self-shadowing check in 0bc79c6