Merge OBC package from Buildings to IBPSA

[mwetter]

This closes #1944

It also moves the round function in the math package as it is used in various Elementary Blocks, and it moves some Composite Control blocks that are likely of general interest.

[FWuellhorst]

@mwetter I will look into the CDL package in the upcoming days, just noticed a minor naming issue outside of that package.

[FWuellhorst]

Buidlings. is still used in some places

[FWuellhorst]

Aside from that comment, the documentation and naming looks ok.
However, you maybe should note in the wiki on naming that you chose a different naming approach for CDL package, as this is heavily oriented at the MSL package or maybe the standard.
Else, you have a lot of complete words and control specific terms in there, not listed as possible exceptions from your naming rules.

Otherwise, I only have two requests:

• Add a central UsersGuide on what this package is and why one should use it. You can refer to existing doc elsewhere if you want.
• Maybe state in that UsersGuide or model doc what the difference to the MSL blocks are, and if changing them is as easy as replacing the MSL block, e.g. and with the one in CDL. Looking at the models, I sometimes do not get why you needed to duplicate a lot of stuff from MSL. Avoid inheritance is one reason, but why add e.g. RealInput again? If switching is easy, do you have a script to automatically switch, if possible? Also, are all blocks exactly the same in terms of functionality, e.g. IBPSA.Controls.OBC.CDL.Logical.Timer? I directly see you added the passed option, but don't get why you did not just compose a new block out of the standard timer and a greater threshold.