Add constant text source for min/max date values

Min/max bounds can now be set as a static "yyyy-MM-dd" string in addition to a DateTime attribute.

Min / max support

• Added support for a minimum and maximum date to be defined, limiting the date range the user can choose from
• Fixed an issue with the formatting of months

Marketplace release

Initital Mendix MarketPlace release

Pre-release

0.9.0

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