Resolves #33: Remove Boost, use C++11

[IanTheEngineer]

It may make sense to branch to melodic-devel prior to adding this commit.

• Replaced boost::trim with C++11 lambda implementation of string trimming
• Replaced all boost::shared_ptr with std::shared_ptr These changes were tested with all of the catkin tests provided, and passed.

[rhaschke]

... or just move the file to src/ to avoid installing it

I prefer this as it facilitates later reuse in another context.

[rhaschke]

Hi @IanTheEngineer, I'm wondering why you want to get rid of boost::trim at all? I totally agree that it makes sense to switch from boost::pointers to std::pointers. However, why should we not re-use other boost utility functions? I don't see the point of inserting header-only code (like trim) all around, instead of using, well-maintained boost code, also header-only. @v4hn, @davetcoleman What should be our policy regarding boost code?

[IanTheEngineer]

@rhaschke I don't have a particularly strong opinion on using boost::trim or not. The goal was just to use the tools afforded by C++11 where possible. These lambdas are pretty straightforward replacements for trim, but if we decide to leave boost as a build dependency just for trim, that's entirely acceptable.

[IanTheEngineer]

@rhaschke if things looks good, I can squash everything down into one commit.

[davetcoleman]

I agree boost is preferred over custom code, but should be replaced where possible by std

Thanks @IanTheEngineer !

[v4hn]

I think everyone agrees here already. If Boost offers functions that simplify our code base, then feel free to use them. There is no particular reason to remove them either, unless the standard offers equivalent solutions.