General replacement of push_back for emplace_back where appropriate.

[svenevs]

@SergioRAgostinho can you delete the card you put on the migration project and "convert this issue to a card" instead? That will enable a conversation to be attached.

I am indebted to PCL, and am happy to slowly whittle away at this. Having it as an issue will make it easier for you all to ping me on this issue after 1.9 is out and hash out the ideal work-flow (e.g. I fork off an emplace_back branch and continually re-base?).

[SergioRAgostinho]

Thanks. Done.

I'll ping you once we enable the flags. I'm gonna assign this to you in the meantime.

[SergioRAgostinho]

You can kick it off if you feel like it. The flags are already merged.