i3: use variables to define workspaces once
i3: use variables to define workspaces once

We use workspace names in three places:

1. Switching to workspace
2. Moving window to workspace
3. Starting application in specific workspace

Until now, if a workspace name changed I had to change it in all three
places. Only now it occured to me that I could use variables. I feel a
bit stupid. :D

lathan/dotfiles,lathan/dotfiles,lathan/dotfiles,lathan/dotfiles,lathan/dotfiles