update.rs: better support for structuring the book
update.rs: Add more characters to the HTML escaping function
editor: don't optimze code (reduce chances of a timeout)
editor: set output font to monospace
hello: introduce the live code editor
print: fix style and a FIXME
literals: Fix style, simplify (remove section about types)
variables: split, talk about scope and shadowing
type: split, talk about literal suffixes
expression: remove type annotations and the definition of a block
if-else: merge source files in one
loops: rename to loop and split
for: fix style, clarify that range takes steps of one
functions: rename to fn, more details about the `()` return type
tuples: fix style
match: split and fix style
structs: fix style
generics: fix style
box: fix style, drop imports
raii: fix style