#5607 typedef System::rank_type

[Dan Eble]

1. break-substitution: typedef System_range to clarify code

Call an interval of System rank a "System_range" rather than a "Slice."

Though both of these are currently Interval_t<int>, there is code that
stores System ranks in shorts. At some point, it might make sense to
change System_range to Interval_t<short> for consistency.</short></int>

1. typedef System::rank_type

Code in break-substitution.cc previously assumed that there would not
be more than 32k systems. This centralizes that assumption in System
and checks for programming errors.

https://codereview.appspot.com/581270043

[Anonymous]

Passes make, make check and a full make doc.

[Anonymous]

Patch on countdown for Nov 25th

[Anonymous]

Patch counted down - please push

[Dan Eble]

commit 000d9cfc986c2b8a4f7f0ffdfbbe25aeed1bac63
Author: Dan Eble <nine.fierce.ballads@gmail.com>
Date:   Mon Nov 18 10:02:30 2019 -0500

    Issue 5607/2: typedef System::rank_type
    ...

commit 1e11c0a21f2003800165b138a5eaf9e0d88a3df7
Author: Dan Eble <nine.fierce.ballads@gmail.com>
Date:   Mon Nov 18 10:02:30 2019 -0500

    Issue 5607/1: break-substitution: typedef System_range to clarify code
    ...