This fixes issue #72.

When using [iAssert ... with ">[]"], we should not use [tac_assert_persistent], and eliminate the modality instead.

This patch is still not ideal, because some modalities (e.g., later) preserve persistence.

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.

Also add "Local" to some Default Proof Using to keep them more contained

This fixes issue #51.

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