Reorganize scanCallback and add comments

[marcelino-pensa]

This PR has no functional changes, it only reorganizes the scanCallback function while adding comments. I really hope that the changes in here will be appreciated as a natural code hygiene. I am totally open for suggestions, criticism, comments to make this better!

Most importantly, the scanCallback has a lot of nested if/else statements, and I un-nested some of them for readability.

Here are the main changes done in this PR:

• Un-nesting some if/else statements for better readability
• Adding comments to some chunks of code
• Made some variables snake_case
• Usage of google's c++ style guide for curly bracket usage: -- The open curly brace is always on the end of the last line of the function declaration, not the start of the next line. -- The close curly brace is either on the last line by itself or on the same line as the open curly brace. -- There should be a space between the close parenthesis and the open curly brace.

[StefanFabian]

Thank you for the reformatting and documentation efforts! I would prefer the ROS Style Guide wrt to the curly bracket placement to keep it consistent with most of the code in this project. Changing the signature of rosPointCloudToDataContainer to void looks good to me.

[marcelino-pensa]

@StefanFabian thank you for the review! I made the modifications you requested, and it should be good to go for another round of reviews Another question I have concerns the function rosLaserScanToDataContainer, which is also bool but always returns true. Should I also make it void?

[StefanFabian]

Sure. Sounds good to me.

[marcelino-pensa]

Done! should be good to go now

[StefanFabian]

Looks good to me. Thank you for your contribution!