Adding edit options to winreject

#### :exclamation: Please, do not merge yet!

This branch is work in progress on editing the `eegDb` database from the level of `winreject()` (that should change name to something like `eegDb()`, `dbshow` or `eegDb_show()`...)
The updates are a bit of a mess, sorry. I will tidy up my git practices in near future.

#### Major updates

:black_circle: `recoverEEG` now checks for filter plugin (#37)
:black_circle: pressing `ctrl + e` opens fuzzy menu with lots of commands that allow to edit `eegDb` from the gui level (not all will be functional in this PR however). Options to change the following are available:
- [x] filtering
- [x] multiselection
- more will come with later updates

:black_circle: `winreject` now uses link functions (`linkfun_` prefix) in some gui <--> gui calls
**link functions** are separate functions that link one GUI with another one or with another function. More specifically (in `winreject`) link functions run smaller GUIs (asking for settings etc.) get the data from these GUI and act on it (apply settings to `eegDb` structure).
:black_circle: introduces some enhancements to `fuzzy_gui_test` - now it is named `fuzzy_gui`:
- [x] scroll bar
- [x] customization