Update Snippet Order

[cwarden]

Is your feature request related to a problem? Please describe.
It would be helpful to be able to change the order of snippets within a folder.

Describe the solution you'd like
Some options that would be useful:

• Ability to move snippets up and down manually with J and K key bindings
• Always sort by modification date descending
• Options to change sort order, by name, creation date, modified date

Describe alternatives you've considered
Keeping track of the current snippet within each folder would partially solve the problem as well.

Additional context
When starting nap, I usually want to edit either the most recently edited snippet, the most recently edited snippet in a different folder, or one of the most recently edited snippets.

[cwarden]

Describe alternatives you've considered
Keeping track of the current snippet within each folder would partially solve the problem as well.

See #38

[cwarden]

Is your feature request related to a problem? Please describe.
It would be helpful to be able to change the order of snippets within a folder.

Describe the solution you'd like Some options that would be useful:

• Ability to move snippets up and down manually with J and K key bindings

See #40