C++11 conversion

[neheb]

Cleans up the code a bit with modern techniques. Some size improvements.

Still compatible with uClibc++. Only needs a modern C++ compiler (GCC 4.8.1).

[csonsino]

My Jenkins job is failing a standard Linux build (not OpenWrt) because I don't have -std=c++11 in my CXXFLAGS. Can we add this, and where would be the best place- configure.ac?

[neheb]

Hmm? GCC has defaulted to C++11 since 4.8.

configure.ac is a good place to add, yes.

[csonsino]

Well I got it to compile fine by adding the -std=c++11 to my Jenkins build script, but I'd prefer if it built without having to include that.

Jenkins is running on an Ubuntu 16.04 box:
gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.11)

Running this magic command seems to indicate that c++ 1998 (or maybe 2003?) is the default:

$ g++ -dM -E -x c++  /dev/null | grep -F __cplusplus
#define __cplusplus 199711L

[neheb]

Ah yes GCC changed their policy regarding that with GCC7. They default to highest stable version now.

One reason for the C++11 changes is smaller compiled size.

[neheb]

Rebased.

[neheb]

Merged your PR.