Initial implementation of exces

- Contains the first example and a rudimentary build system.
Removed temporary code
Updated the allocation of components in storage
Multiple changes

- Added component storage space reservation.
- Added entity keys to manager for faster access.
- Added reference counted shared_component.
- Added new overload of for_each to manager.
- Added the select* functions to manager.
Multiple changes

- Minor optimizations in manager.
- Added new overloads of for_each.
- Added a new example.
- Added the component_name template.
- Added the visit_each function.
- Added entity I/O operators.
- Minor update of readme.
Multiple changes

- Renamed storage::key_t to component_key.
- Added the manager::has<Component>() function.
- Added the manager::entity_range::front_component<Component>() function.
- Minor optimizations and code cleanup in manager.
- Added a new example.
Multiple changes
Reorganization of headers

- Moved implementation details into the exces/aux_/ subfolder.
Added a configure script

- Also added a bash-completion script for the configure script.
Minor changes to the build system

- Added detection of Boost.
Documentation update
Multiple changes

- Removed the operator -> from shared_component.
- Added support for flyweight components.
- Added the replace functions to manager and storage.
Multiple changes

- Fixed a problem in the classification implementation.
- Added 2 new examples.
Multiple changes

- Renamed the former entity class to uuid_entity.
- Added a customizable entity<Group> metafunction that returns the entity type.
- Fixed a problem in shared_component.
- Added the write functions to manager.
- Updated the examples.
Documentation update
Minor documentation update in manager
Muptiple changes

- Documentation update in manager.
- Fixed a bug in manager::copy* functions.
Multiple changes

- Added instructions to build the doxygen html documentation.
- Minor documentation updates.
Added the create* functions to manager
Updates in classifier

- Added the entity filter function to classifier.
- Fixed a bug in the move constructor.
- Documentation update.