Massive theme overhaul. Added new theme, new navbar structure, make search bar work, added navbar button, reworked all modals, made sessions to be destroyed on session close, added dynamic footer (fixed if there is not scroll), reworked language dropup menu, made user photo clickable (leads you to your profile) on pantallaPrincipal, and some fixes here and there. Made footer modular so overall the page is less bloated.