Convention routing

The files in ./src/pages are automatically turned into routes. It's called "Convention Routing" in other projects and we'll use the same name.

Examples

Page file	HTTP route
`./src/pages/about.imba`	`/about`
`./src/pages/contact.md`	`/contact`
`./src/pages/help.html`	`/help`
`./src/pages/products/index.imba`	`/products`
`./src/pages/products/[productId].imba`	`/products/:productId`
`./src/pages/_cant_see_me.imba`	none, hidden

The parameters are marked with the : like :productId and standard for most servers.

Filenames starting with an underscore _ are not made into routes.