This way, it can be used with `iApply`.

Replace/remove some occurences of `persistently` into `persistent` where the property instead of the modality is used.

I have reimplemented the tactic for introduction of ∀s/pures using type
classes, which directly made it much more modular.

persistent context.

Given the source does not contain a box:

- Before: no-op if there is a Persistent instance.
- Now: no-op in all cases.

This enables things like `iSpecialize ("H2" with "H1") in the below:

  "H1" : P
  ---------□
  "H2" : □ P -∗ Q
  ---------∗
  R

This fixes issue #81.

- Allow framing of persistent hypotheses below the always modality.
- Allow framing of persistent hypotheses in just one branch of a
  disjunction.

- Support for a `//` modifier to close the goal using `done`.
- Support for framing in the `[#]` specialization pattern for
  persistent premises, i.e. `[# $H1 $H2]`
- Add new "auto framing patterns" `[$]`, `[# $]` and `>[$]` that
  will try to solve the premise by framing. Hypothesis that are
  not framed are carried over to the next goal.

This fixes issue #72.

For example, when having `"H" : ∀ x : Z, P x`, using
`iSpecialize ("H" $! (0:nat))` now works. We do this by first
resolving the `IntoForall` type class, and then instantiating
the quantifier.

Instead of doing all the instantiations by invoking a single type
class search, it now performs the instantiations by invoking
individual type class searches. This a.) gives better error messages
and b.) works when `xj` depends on `xi`.

In the following ways:
- When having `P → Q` it will now also work when the spatial context
  is non-empty.
- When having `∀ x : A, Q` it will now do an `iIntros (_)`.

This fixes issue #62.

This patch was created using

  find -name *.v | xargs -L 1 awk -i inplace '{from = 0} /^From/{ from = 1; ever_from = 1} { if (from == 0 && seen == 0 && ever_from == 1) { print "Set Default Proof Using \"Type*\"."; seen = 1 } }1 '

and some minor manual editing

    The idea on magic wand is to use it for curried lemmas and use ⊢ for uncurried lemmas.

Use COFEs only for the recursive domain equation solver

The old name didn't make much sense. Also now we can have
pure_False too.

This way we avoid the env_cbv tactic unfolding string related stuff
that appears in the goal and hypotheses of the proof mode.

The old choice for ★ was a arbitrary: the precedence of the ASCII asterisk *
was fixed at a wrong level in Coq, so we had to pick another symbol. The ★ was
a random choice from a unicode chart.

The new symbol ∗ (as proposed by David Swasey) corresponds better to
conventional practise and matches the symbol we use on paper.

That's like what we are doing when instantiating an arrow or wand.