Enhancements to data selection panel

[x] GET and DOWNLOAD buttons collide when the page is too narrow
[x] Matrices --> PSUT matrices
[x] Rephrase "Select type of plot" to "Choose visualization" or simply "Visualization"
[x] Don't show "IEAEWEB2022" if the user lacks access to IEA data. Even better, find a way to reduce access to all future IEA data, too.
[x] "Get country(s)" --> "Country(ies)". Also, do we have the ability to choose multiple countries yet?
[x] Selected by method --> Method. However, the list of methods should be populated by types present in the data. At the moment, we have only "PCM".
[x] For energy type --> Energy type. Spell out E and X (Energy, Exergy)
[x] To last stage --> Last stage. Radio buttons? We have only Final and Useful last stages at present (and probably far into the future)
[x] IEA, MW should also have "Both" as an option.
[x] Including NEU --> Include NEU
[x] Set reasonable defaults such that if the user just clicks "GET" a plot will be produced.
[x] Remember these selections for the next time the user logs in.

Energy-Visualizer / mexer