Inline of functions should be improved

[tesonep]

• Correctly generate comments for inlining functions (aka... start of inlined, end of inlined)
• When an inlined function is used as an expression it should check if the function can be put as an expression (aka, does not have things that are not expressions, e.g. while, goto)
• Check the semantics of the inline pragma.

[PalumboN]

Today we were talking to avoid if expressions cond ? x : y and list expressions (expr1, expr2, expr3) in the generated C code.

• This will simplify the Slang translation.
• Check if performance is degraded.