Minisom Versions Save

• improved structure of hexagonal topology - thanks to @aznt00th
• improved pca initialization
• fixed bug affecting the topographic error
• the main notebooks containing the examples are now covered by CI

• Introduce use_epochs parameter, when True it will keep learning rate and decay constant for an entire epoch. Thanks to @jriege555 for submitting this change
• Topographic Error can now be computed also for hexagonal grids. Thanks to @TharindaDilshan
• Fixed issue with pca initialization

• Activation functions can now be defined via callables, thanks to @chicodelarosa
• The method distance_map now has the parameter neighbour_average that allows the user to normalize the distances. Thanks to @lbugnon

License change.