#209 Implemented demo version of sequences

[Jan-Sandr]

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Closes #209

Solution description

Brief implementation of sequences without any input check. Added new class Sequence.cs which is inheritance of Function.cs Also some updates in main class because requirement of axis labels updates based on if is sequence or function.

I confirm that

• [x] Application is runable
• [x] All added code is commented
• [x] I ran both code cleanup profiles
• [x] All tests passed