Improved parser and renderer

src/graphics/opengl/Window.cpp

src/graphics/opengl/components/TextComponent.cpp

src/graphics/opengl/components/TextComponent.h

src/html/HTMLParser.cpp

src/html/HTMLParser.h

src/html/Node.h

src/html/TagNode.cpp

src/html/TagNode.h

src/html/TextNode.cpp

src/html/TextNode.h

src/html/elements/H1Element.cpp

src/html/elements/H1Element.h

src/html/elements/H2Element.cpp

src/html/elements/H2Element.h

src/html/elements/H3Element.cpp

src/html/elements/H3Element.h

src/html/elements/LIElement.cpp

src/html/elements/LIElement.h

src/html/elements/PElement.cpp

src/html/elements/PElement.h