add support for zsh with env and env hook
fixed origin path in comment of template
remove use of `which` and use `ls` over `find`

`which` is not necessary when the command is
first stored in a variable before being executed

also in once case the user of `find` could be
simplified by just using `ls`
ament_cmake_index: support multiple workspaces
add better comments for aliases workaround
fix alphabetical ordering
alphabetical ordering
Merge pull request #1 from ament/fix_osx

Fix for OS X, which does not support -printf in find