Adding PLANNED_FEATURES.md

This is where I will be writing more plan-related information.
PLANNED_FEATURES.md: Some additional information.
PLANNED_FEATURES.md: Words are annoying and so are 80-column limits.
PLANNED_FEATURES.md: Remove 80-column line limit and add a bit more.
Merge branch 'master' into planning

Signed-off-by: Kristofer Rye <kristofer.rye@gmail.com>
PLANNED_FEATURES: Add another suggestion.
Merge branch 'planning' into 'master'.

This constitutes a movement of the currently-planned features into the
main branch.

Signed-off-by: Kristofer Rye <kristofer.rye@gmail.com>