Read available commands dynamically

`git elegant commands` will read commands dynamically. This change
allows having more stable results of other tests as the `commands`
command is often used in other commands or tests. For instance,
if we add a new command, it will be found automatically and
1. a help will be verified for it
2. `tests/git-elegant-commands.bats` will fail by requiring updates with
the data about the new command.

#118

libexec/git-elegant-commands

@@ -28,15 +28,8 @@ MESSAGE
 }
 
 default() {
-    echo "acquire-repository"
-    echo "clone-repository"
-    echo "init-repository"
-    echo "start-work"
-    echo "save-work"
-    echo "deliver-work"
-    echo "accept-work"
-    echo "obtain-work"
-    echo "clear-local"
-    echo "commands"
-    echo "amend-work"
+    local PREFIX="git-elegant-"
+    for FILE in $(ls -1 ${BINS}/${PREFIX}*); do
+        echo $(basename ${FILE} | sed "s/${PREFIX}//")
+    done
 }

tests/git-elegant-commands.bats

@@ -22,10 +22,10 @@ teardown() {
         "amend-work"
     )
     check git-elegant commands
-    for command in {0..12}; do
-        [ "${lines[$command]}" = "${COMMANDS[$command]}" ]
+    [ ${#lines[@]} -eq ${#COMMANDS[@]} ]
+    for command in ${COMMANDS[@]}; do
+        [[ "${lines[@]}" =~ "${command}" ]]
     done
-    [ ${#lines[@]} -eq 11 ]
 }
 
 @test "'commands': default exit code is 0" {