Build shell is a system to help manage differen development environments

The environments are defined in files containing a json like format. These files
are called buildset files. The system will help pull down sources, configure,
build and install the different projects

A project defined in a buildset can have a few properties. These are:
scm : object - object containing information about the scm the project uses
                this information wiill determin how the projects are pulled
                down

env : object - object containing information about environment variables that
                should be defined before the build, only for this build or
                after the build

no_install : boolean - property which indicates the install step should be skipped

configure_args : string - property which is passed to the configure script. This
                is additional configuration, as the configure scripts should
                allready handle the "prefix".

default_skip : boolean - if this property is set, this project will be skipped
                in all build steps. Build steps are clean, deep-clean,
                pre_build, configure, make, install, post_build. For projects
                containing this flag to be build they have to be specified
                specifically. Normally like:
                $ bs build some_project
no_shadow : boolean - this property defines that a project can not do shadow
                builds/out of source builds. If a buildset it set up to do
                shadow build, then projects that have this flag will still do in
                source builds

clean_environment : boolean - projects with this flag will use a clean
                environment. That means, unload current loaded buildset, and
                only set environment variables defined for this project. Also
                the regular environment variables like PATH and LD_LIBRARY_PATH
                will not be set. Note that PATH and LD_LIBRARY_PATH will only be
                set if lib and bin are defined in the install directory, and
                install directory is not /usr