Extrinsic calibration add calc button

Currently, when opening a new 3dc file, the following warning shows.

Previously this warning was just to the log window, therefore it went unnoticed. Now that the warning is more user-facing, we should ask ourselved what exactly is the order of operations that we have and when should we warn; when should we start calibration; etc.

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from comment below

After some discussion with Maik:

Adding a third button calc which starts the calibration and using load/fetch only to load data is a valid way to circumvent this error message.

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Note: May want to change auto from intrinic calibration into calc as well