Feature/rework periodic value deserialisation

[FelixMau]

Description

To implement multiperiod feature multiple values might be passed for one facade. Therefore implemented array values that need to be unpacked to either act as periodical values, yearly values or as full series.

Fixes #151

Type of change

Please tick or delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

Please tick or delete options that are not relevant.

• New and adjusted code is formatted using the pre-commit hooks
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have added new features/fixes to the CHANGELOG
• I have added my name to AUTHORS

[FelixMau]

Unfortunately test failes when a periodical changing value for "capacity" is added.

Deserializing for

• storage 'capacity_cost'
• link 'capacity_cost'
• dispatchable 'capacity' (breaking and removed in #1be182b)
• volatile 'marginal_cost'

[FelixMau]

Setting Capacity to periodical changing value failed as intended by solph when building flows.
Changing nominal values are only allowed if Investment is set.

Therefore added capacity periodical values to storage (since it is Investment object)

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Note: Improvment in _flow Code style using else instead of 'pre setting' values could be improved. Throwing error might also be useful sometime

[nailend]

This looks great. Thanks a lot