task: Add taskopen alias

Added alias within taskwarrior to invoke taskopen through
(unsurprisingly) `task open`. Importantly, the difference to other
taskwarrior commands is that the number of the task to open should come
AFTER the command, not before as a filter as for all the others. Perhaps
that can be changed in the future.

taskwarrior/.config/task/taskopenrc

@@ -1,4 +1,5 @@
 [General]
+EDITOR = nvim
 taskbin = task
 path_ext = /usr/share/taskopen/scripts
 

taskwarrior/.config/task/taskrc

@@ -23,6 +23,7 @@ weekstart=monday
 
 # Make daily burndown default alias
 alias.burndown=burndown.daily
+alias.open=exec taskopen "--config=${XDG_CONFIG_HOME:-$HOME/.config}/task/taskopenrc"
 
 # Sort the columns a little differently
 active.indicator=>