Enforce variable scoping

[deepanjan90]

Variable scope

1. Global - defined in init.gyro
2. File - defined in any *.gyro file
3. For Inline - defined as part of a @for loop initializer
4. For Body - defined in the body of a @for loop

Scoping rules

1. Global - accessible from every where, cannot be redefined any where
2. File - accessible only from the file, cannot be redefined any where in the file
3. For Inline - accessible from inside the body of the @for, cannot be redefined anywhere in the body
4. For Body - accessible in the body of the @for loop, cannot be redefined anywhere in the body