Boost.Build Python port overall status

What works

• Interface between Python and Boost.Jam build engine is finished.
• Project loading and target declaration works
• Top-level code is ported, including getting build request, loading configuration files and projects and building/cleaning.
• A simple project with a 'make' rule loads and builds fine

Status of porting code modules

The below table documents the state of files in the 'build' directory. There, 'done' means the file is totally done, 'almost' means the file is essentially done, but maybe we tweaks are necessary as other files are ported and 'pending' is not yet there.

File	Lines	Status
targets.jam	1550	almost
feature.jam	1284	pending
virtual-target.jam	1231	pending
generators.jam	1214	pending
project.jam	1018	pending
property.jam	694	pending
toolset.jam	510	pending
property-set.jam	464	pending
type.jam	370	pending
build-request.jam	301	pending
modifiers.jam	241	pending
scanner.jam	151	pending
alias.jam	75	done
version.jam	20	pending

Short-term goals

• Port remaining core modules.

Medium-term goals

• Design proper error reporting mechanism
• Port all of tools