Make `fmap` left associative.

See merge request robbertkrebbers/coq-stdpp!16

This follows the associativity in Haskell. So, something like

  f <$> g <$> h

Is now parsed as:

  (f <$> g) <$> h

Since the functor is a generalized form of function application, this also now
also corresponds with the associativity of function application, which is also
left associative.

This is similar to `f_equal/=`.

Use `stdpp_scope` for all notations.

See merge request robbertkrebbers/coq-stdpp!17

Provide a pretty-printer for [nat].

See merge request robbertkrebbers/coq-stdpp!15

Minor documentation fixes

See merge request robbertkrebbers/coq-stdpp!14

The documentation for some typeclasses used the wrong
names for these typeclasses.

Notation for disjointness: replace ⊥ with ##, so that ⊥ can be used for bottom.

See merge request robbertkrebbers/coq-stdpp!12

This addresses some concerns in !5.

Add monadic `;;` and change level of the do-notation to 100

See merge request robbertkrebbers/coq-stdpp!10

This way, we will be compabile with Iris's heap_lang, which puts ;;
at level 100.

Add more lemmas for gmap uncurry

See merge request robbertkrebbers/coq-stdpp!9

Add more properties of intersection_with for fin_maps

See merge request robbertkrebbers/coq-stdpp!7

Add lemma lookup_gmap_uncurry_empty

See merge request robbertkrebbers/coq-stdpp!8