⚠️ Rework completely how transitions works

- Use Svelte/Sapper native if and transitions to show either the page content or the loader, then load each page animationIn
- Code is safe on SSR side, using process.browser on this if
- The <main> element is on position absolute to fade nicely the different pages
- Code cleaning

src/utils/store.js

@@ -1,4 +1,3 @@
-// Svelte
 import { writable } from 'svelte/store'
 
 // Define environment
@@ -25,17 +24,14 @@ export let currentLocation = writable()
 export let currentPhotos = writable()
 
 // State
-export let pageReady = writable(false)
-export const pageTransition = {
-   onAnimationEnd () {}
-}
+export let pageReady = writable(false, () => {})
+export let firstLoad = writable(true)
 export let fullscreen = writable()
 
 
 /* ==========================================================================
    Animation related
 ========================================================================== */
-export const transitionDelay = 1400
-export const transitionNormal = 1400
-export const transitionLong = 1800
-export const transitionPanelIn = 700
+export const animDelay = 800
+export const animDuration = 1400
+export const animDurationLong = 1800