+ added parameterModel

+ added function to get unit from entire author system content by its UUID
- in contextInfoModel: removed unnecessary complexity in value object
+ in contextInfoModel: added each part of former value object as context info property + getter and setter functions for each
# completed changes towards consistent usage of models: contextInfo, parameters, unit, authorSystem
# completed changes in checkInformation(), drawing information from model structure instead of view
# renamed parameter input and select fields and divs with generic ID "parameter"+i and "divParameter"+i, resp.
# untangled event handlers for clicked or dragged units and properties tab from "blob" activateFunctionalities()
# replaced (use and function of) global var global_currentInputUnitName with global var currentUnitUUID
# made variable currentConnectionID global