Path processing
---------------
Need rules that will work for both the existing scenario (B) and the new
scenario (A):


    _
   / \
  / _ \
 / ___ \
/_/   \_\
---------

root    = ../
package = suppliers/colony             <--- /suppliers/colony
import  = ../map/return/colony         <--- /map/return/colony

mapimport = ../../suppliers/colony/gl  <-- /suppliers/colony/gl


      this is the root
     /                \
    v                  v
1) <..>/map/return/ | <..>/../suppliers/colony/gl
     = ../suppliers/colony/gl
            ^^^^^^^^^^^^^^^^
            \              /
              package name

2) strip root||(package base) from package import
     = ../map/return | <../suppliers/>colony/gl
     = colony/gl
       ^^^^^^^^^
                ` The relative path from package



 ____
| __ )
|  _ \
| |_) |
|____/
-------

what about normal includes?


root    = ../
package = suppliers/colony   <--- /suppliers/colony
import  = ../common/foo      <--- /common/foo

subimport = bar/baz          <--- /common/foo/bar/baz


       one has root, other does not
      /
     v
1) <..>/common/ | bar/baz
     = ../common/bar/baz

2) strip root||(package base) from package import
     = ../common/bar/baz
       ^^^^^^^^^^^^^^^^^
                        ` no such prefix,
                          so this is the relative path