Change from unit="1" to unit="" to avoid unit issues.

[HansOlsson]

Closes #3878

[mestinso]

Instead of making the change here, why not just change the default units for gain in the various MSL Blocks (Math.Gain, Continuous.Integrator, etc.)? It seems to me the choice of setting the units for gain = "1" wasn't a good general assumption in those components and they should just be set to "". I can see the logic in the context of a "voltage gain" or something along those lines, but I don't think it's generally correct assumption in other contexts (controls etc.) like in the examples here. Thoughts?

[HansOlsson]

Instead of making the change here, why not just change the default units for gain in the various MSL Blocks (Math.Gain, Continuous.Integrator, etc.)? It seems to me the choice of setting the units for gain = "1" wasn't a good general assumption in those components and they should just be set to "".

That was also my first reaction, which basically means reverting #227 and I'm open to it.

However, when I looked the number of problematic cases were actually fairly low (as listed in this PR).

But it could be that the cases helped by #227 are also so few that it isn't worth the effort (I see that there are more gain-blocks - but I don't see if unit-checking would do anything for the other cases).

We could even decide to mix&match to e.g. remove unit for Gain, and keep for the others such as Integrator (and thus modify even fewer cases).

[dietmarw]

I would prefer to use the solution presented in #3881 instead.

[HansOlsson]

Since #3881 seems more popular I will close this one. Obviously it can re-opened if that changes.