Initial commit.
Build scripts.
common declarations.

id, info_type, hash_type, error, invalid_id_error declaration.
is_allowed_id() and validate_id() implementation.
Refactoring: hash_type -> hash, info_type -> info.
importer: declaration + convert() implementation.
importers::single partial implementation.
bunsan::factory::instance{,_optional}() usage update.
importers::single::convert() implementation.
importer::m_config semantics was changed.
importer::impl::~impl() implementation.
importer::impl::instance() bug fix.
importers::single bug fix.
importers::single refactoring.
problem::info refactoring.
CMakeLists.txt: integration with bunsan_use_protobuf() macro.
bacs.problem.pb.problem implementation.
buildable implementation.
importers::single was removed.
statement, statement_versions::{copy,pdflatex} implementation.
resource::parse::{time_millis,memory_bytes}() implementation.