machinetalkservice.cpp: gpb::vector -> std::vector

[l29ah]

for newer protobuf compatibility fixes https://github.com/machinekit/QtQuickVcp/issues/279

[l29ah]

The culprit is: commit 39a789e657a52e835c281233b63cc2a6bb387fd4 Author: Adam Cozzette acozzette@google.com Date: Fri Jan 19 16:46:57 2018 -0800

Removed using statements from common.h

These statements pulled a bunch of symbols from the std namespace into
the global namespace. This commit removes all of them except for
std::string, which is a bit trickier to remove.

[machinekoder]

Thanks.