Fixed c++ variant in linux Makefile for the IDE, Build directory handled properly

Leaving out -std=c++03 caused g++ to default to c++98.
This caused compilation to fail because linux is defined as 1 in the preprocessor for c++98.
This would probably also have worked with any other newer version. c++0x and c++11 works at least.
The Build directory was also not created by the Makefile, which caused make to complain.