ENH: Improved 'del ITEM# TERM' command.

- Condensing whitespace around TERM into a single space and removing leading/trailing spaces if at the beginning/end of the task.
- Proper error message if TERM not found.
- Aligned verbose removal message with the verbose output of the 'replace' command.
In addition, removed (accidental) printing of the task (without leading ITEM#) when checking for existence of the task; using empty check of task text as done elsewhere.

tests/t1800-del.sh

@@ -0,0 +1,112 @@
+#!/bin/sh
+
+test_description='basic del functionality
+'
+. ./test-lib.sh
+
+test_todo_session 'del usage' <<EOF
+>>> todo.sh del B
+usage: todo.sh del ITEM# [TERM]
+=== 1
+EOF
+
+test_todo_session 'del nonexistant item' <<EOF
+>>> todo.sh -f del 42
+42: No such task.
+=== 1
+
+>>> todo.sh -f del 42 Roses
+42: No such task.
+=== 1
+EOF
+
+cat > todo.txt <<EOF
+(B) smell the uppercase Roses +flowers @outside
+(A) notice the sunflowers
+stop
+EOF
+test_todo_session 'basic del' <<EOF
+>>> todo.sh -p list
+2 (A) notice the sunflowers
+1 (B) smell the uppercase Roses +flowers @outside
+3 stop
+--
+TODO: 3 of 3 tasks shown
+
+>>> todo.sh -f del 1
+1: (B) smell the uppercase Roses +flowers @outside
+TODO: 1 deleted.
+
+>>> todo.sh -p list
+2 (A) notice the sunflowers
+3 stop
+--
+TODO: 2 of 2 tasks shown
+EOF
+
+cat > todo.txt <<EOF
+(B) smell the uppercase Roses +flowers @outside
+(A) notice the sunflowers
+(C) stop
+EOF
+test_todo_session 'basic del TERM' <<EOF
+>>> todo.sh -p list
+2 (A) notice the sunflowers
+1 (B) smell the uppercase Roses +flowers @outside
+3 (C) stop
+--
+TODO: 3 of 3 tasks shown
+
+>>> todo.sh del 1 uppercase
+1: (B) smell the uppercase Roses +flowers @outside
+got 'uppercase' removed to become
+1: (B) smell the Roses +flowers @outside
+
+>>> todo.sh -p list
+2 (A) notice the sunflowers
+1 (B) smell the Roses +flowers @outside
+3 (C) stop
+--
+TODO: 3 of 3 tasks shown
+
+>>> todo.sh del 1 "the Roses"
+1: (B) smell the Roses +flowers @outside
+got 'the Roses' removed to become
+1: (B) smell +flowers @outside
+
+>>> todo.sh del 1 m
+1: (B) smell +flowers @outside
+got 'm' removed to become
+1: (B) sell +flowers @outside
+
+>>> todo.sh del 1 @outside
+1: (B) sell +flowers @outside
+got '@outside' removed to become
+1: (B) sell +flowers
+
+>>> todo.sh del 1 sell
+1: (B) sell +flowers
+got 'sell' removed to become
+1: (B) +flowers
+EOF
+
+cat > todo.txt <<EOF
+(B) smell the uppercase Roses +flowers @outside
+(A) notice the sunflowers
+(C) stop
+EOF
+test_todo_session 'del nonexistant TERM' <<EOF
+>>> todo.sh del 1 dung
+1: (B) smell the uppercase Roses +flowers @outside
+'dung' not found; no removal done.
+=== 1
+
+>>> todo.sh -p list
+2 (A) notice the sunflowers
+1 (B) smell the uppercase Roses +flowers @outside
+3 (C) stop
+--
+TODO: 3 of 3 tasks shown
+EOF
+
+test_done