Improve Research Notes handling

[cwittern]

Is your feature request related to a problem? Please describe.
Research Notes do not have structure. They also do not allow searching
Describe the solution you'd like
Introducing structure might be difficult, but a first step could be using #hashtags, possibly with some support from the interface (like in GitHub, here) and thus building up a vocabulary for things one might want to look for.

This is also related to #96