Fix pos attribute generation

[c71n93]

In this example (taken from src/test/resources/integration/in/basic_cycle/basic_cycle.xmir):

[] > classA
  classB > @
  [] > doA
    stdout > @
      "A"

[] > classB
  classA > @
  [] > doBA
    ^.doA > @

XMIR listing of object classB looks like this:

<o abstract="" line="9" name="classB" pos="0">
   <o base="classA" line="10" name="@" pos="2"/>
   <o abstract="" line="11" name="doBA" pos="2">
      <o base="^" line="12" pos="4"/>
      <o base=".doA" line="12" method="" name="@" pos="5"/>
   </o>
</o>

DDR gives result transformed XMIR with such classB object (taken from src/test/resources/integration/out/basic_cycle/basic_cycle.xmir):

<o abstract="" line="9" name="classB" pos="0">
   <o base="classA" line="10" name="@" pos="2" ref="3"/>
   <o abstract="" line="11" name="doBA" pos="2">
      <o base="^" line="12" pos="4"/>
      <o base=".@" line="12" method="" pos="9"/>
      <o base=".doA" line="12" method="" name="@" pos="5"/>
   </o>
</o>

As an EO code, classB object should look like this:

[] > classB
  classA > @
  [] > doBA
    ^[email protected] > @

So pos of .@ equals "5" and pos of .doA equals "7". But this is not the case in the XMIR file.
We either need to delete thepos attribute for objects that are related to DDR working process, or handle their pos attribute correctly.