Allow comments between variable declarations

[Danysan1]

These changes aim to fix #883 by skipping comment lines when analysing variable blocks to show reference counts.

Before

# Foo
@foo = abc
# Bar
@bar = xyz
@quz=ijk

GET https://abc.xyz?foo={{foo}}&bar={{bar}}

After

Tests

I have no experience whatsoever with this codebase so I'm not sure wether changing this file is enough or other files need to be changed, but in my tests it worked as expected:

# Foo
@foo = abc
# Bar
@bar = xyz
@quz=ijk

GET http://urlecho.appspot.com/echo?body={{foo}}+X+{{bar}}+X+{{bar}}

[Huachao]

Add space between if and (

[Danysan1]

Done in 27caf44

[Huachao]

@Danysan1 Thanks, merged.