ENH: Allow listpri filtering via TERM.

This even simplified the argument handling, since there can be no invalid priority any more; all other strings are taken as TERMs. And the check for empty ${1:-} was superfluous, anyway. Apart from these simplifications, it's basically just passing $@ to _list.

tests/t1250-listpri.sh

@@ -4,13 +4,6 @@ test_description='list priority functionality
 '
 . ./test-lib.sh
 
-test_todo_session 'listpri usage' <<EOF
->>> todo.sh listpri ?
-usage: todo.sh listpri PRIORITY
-note: PRIORITY must a single letter from A to Z.
-=== 1
-EOF
-
 cat > todo.txt <<EOF
 (B) smell the uppercase Roses +flowers @outside
 (C) notice the sunflowers
@@ -42,7 +35,7 @@ cat > todo.txt <<EOF
 (n) not a prioritized task
 notice the (C)opyright
 EOF
-test_todo_session 'listpri filtering' <<EOF
+test_todo_session 'listpri filtering priorities' <<EOF
 >>> todo.sh -p listpri
 1 (B) smell the uppercase Roses +flowers @outside
 2 (C) notice the sunflowers
@@ -68,4 +61,35 @@ TODO: 0 of 5 tasks shown
 TODO: 0 of 5 tasks shown
 EOF
 
+cat > todo.txt <<EOF
+(B) ccc xxx this line should be third.
+ccc xxx this line should be third.
+(A) aaa zzz this line should be first.
+aaa zzz this line should be first.
+(B) bbb yyy this line should be second.
+bbb yyy this line should be second.
+EOF
+test_todo_session 'listpri filtering of TERM' <<EOF
+>>> todo.sh -p listpri "should be"
+3 (A) aaa zzz this line should be first.
+5 (B) bbb yyy this line should be second.
+1 (B) ccc xxx this line should be third.
+--
+TODO: 3 of 6 tasks shown
+
+>>> todo.sh -p listpri a "should be"
+3 (A) aaa zzz this line should be first.
+--
+TODO: 1 of 6 tasks shown
+
+>>> todo.sh -p listpri b second
+5 (B) bbb yyy this line should be second.
+--
+TODO: 1 of 6 tasks shown
+
+>>> todo.sh -p listpri x "should be"
+--
+TODO: 0 of 6 tasks shown
+EOF
+
 test_done