#5340 Simplify Spacing_spanner::get_columns

[Dan Eble]

Simplify Spacing_spanner::get_columns

The old algorithm filtered the system's list of columns into a list of
used columns, then searched the filtered list for the endpoints of the
range to return.

The search key was the "rank" of a column, which is its index in the
unfiltered list of columns (see System::add_column). There is
therefore no need to search.

The new algorithm selects the desired range in the unfiltered list and
then filters that.

This commit also removes the unused function Paper_column::compare.

http://codereview.appspot.com/348940044

[Anonymous]

Passes make, make check and a full make doc.

[Anonymous]

Patch on countdown for Jun 13.

[Anonymous]

Patch counted down - please push.

[Dan Eble]

commit bb34e5bbfdcf8d10877b5b85a339416f0a03c39b (HEAD -> pushed/issue-5340-used-columns-in-range, origin/staging)
Author: Dan Eble nine.fierce.ballads@gmail.com
Date: Mon Jun 11 06:47:48 2018 -0400

Issue 5340: Simplify Spacing_spanner::get_columns

The old algorithm filtered the system's list of columns into a list of
used columns, then searched the filtered list for the endpoints of the
range to return.

The search key was the "rank" of a column, which is its index in the
unfiltered list of columns (see System::add_column).  There is
therefore no need to search.

The new algorithm selects the desired range in the unfiltered list and
then filters that.

This commit also removes the unused function Paper_column::compare.