filter: Add another test for numerical queries

The existing test was good for comparisons between columns and numerical
constants, but did not cover comparisons between two numerical columns.

tests/functional/filter/cram/filter-query-numerical.t

@@ -33,3 +33,28 @@ The 'category' column will fail when used with a numerical comparison.
   	'>=' not supported between instances of 'str' and 'float'
   Ensure the syntax is valid per <https://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#indexing-query>.
   [2]
+
+Create another metadata file for testing.
+
+  $ cat >metadata.tsv <<~~
+  > strain	metric1	metric2
+  > SEQ1	4	5
+  > SEQ2	5	9
+  > SEQ3	6	10
+  > ~~
+
+Use a Pandas query to filter by a numerical value.
+This relies on having proper data types associated with the columns. If < is
+comparing strings, it's likely that SEQ3 will be dropped or errors arise.
+
+  $ ${AUGUR} filter \
+  >  --metadata metadata.tsv \
+  >  --query "metric1 > 4 & metric1 < metric2" \
+  >  --output-strains filtered_strains.txt
+  1 strains were dropped during filtering
+  \t1 of these were filtered out by the query: "metric1 > 4 & metric1 < metric2" (esc)
+  2 strains passed all filters
+
+  $ sort filtered_strains.txt
+  SEQ2
+  SEQ3