Core pipeline improvements

[inanevin]

• Get rid of static templates for input engine.
• Introduce input devices and use them over input engine.
• Some headers are messed up, compilation takes too much time. Go over the header files & core structure, remove unnecessary headers.
• Improve public API. Do some header work on LinaPch.hpp
• Go over the encapsulation of internal classes, make sure of variable encapsulation.
• Go over default, copy, assign and move constructors on internal classes. Make sure public API prevents access of construction/destruction of internal Lina classes. Also make sure that their instantiation is done within Lina internally, memory is managed correctly.
• Add some extra common headers.