Latest features and road ahead

[mmedl94]

The main features added since the last review were:

1. Rework of the histogram selection. Now the bars are colored in a way that the user can see the fraction of selected datapoints in each bin.
2. Rework of the init_env function: tkinter/customtkinter apps don't look appealing/modern when launched from Anaconda environments. Therefore, by default init_env now creates a virtual enivronment instead of an Anaconda environment (and also installs the required python version if it isn't already). I believe that package managment is more error prone without Anaconda. Therefore, one can still choose to create an Anaconda environment by init_env(virtual_env = "anaconda"). However, the app won't look good.
3. Addition of the manual tour: By dragging the projection axis heads with the right mouse button one can manually adjust the displayed projection in 2d scatterplots.
4. Addition of feature selection: There are now checkboxes corresponding to the features on the left of the app. By checking and unchecking the boxes one can select the features. How the checkboxes will be displayed in the final product is still open.

Ideas for upcoming features:

1. Local tour: A button to initialize a local tour from the currently shown display.
2. Multi-select: The option to select multiple different subsets.
3. Guided tour: A button to initialize a guided tour that tries to separate the multi-selected groups. Goes hand in hand with 1, but requires 2.