Online - Computation - Accurate/Unreliable height - Rename to RTK (Accurate Height) / Tide (Unreliable Height)

The Problem:
The computation setup can be difficult for users to understand when they start using QINSy.
One of the items is the accurate height and unreliable heights on the positioning systems. 

Proposed Solution:
To make it easier for user to understand what will be used in a computation please rename accurate and unreliable heights to:

1. RTK (Accurate Height)
2. Tide (Unreliable Height)
   • Helps the user to understand that tide is going to be used  (needs to be selected on the heights page of the object)