External references are being inlined

[elyashivlavi]

According to the fix was made in #27,
Now external references are being inlined.
This means that if I have such a spec:

paths:
  /path1:
    parameters:
        - $ref: 'param1.yaml'
  /path2
    parameters:
       - $ref: 'param1.yaml'

Then I will end with 2 inner messages Param1 in the protofile, instead of reusing the existing one... Is this intentional?
I assume it can be changed easily by adding external references to the 'definitions' section of the scheme, instead of inlining them (in external.go file).
WDYT?