Third Alpha pre-release

Systems went from template argument to constructor arguments, which gave the possibility to bind arguments, as well as capturing argument with lambas.
There is also other minor modification along the major ones, like being able to access components from entity::Container methods.
Those changements have been made after trying to use the library in a real context.

Second Alpha pre-release

Pollished version of the 0.1-alpha version, ready to be evaluated by the code review with the documentation up to date

First Alpha pre-release

Have never been used in a real project yet. This version is the first version ever released to be theorically ready to be used.
A lot of problems will probably be found, just need to find them.