Alpha version number for the v5.3.6 release
redo square-bracket related bug fixes from master
release notes
fix unstable/socket loading in windows
  closes PR 13743
(cherry picked from commit 26545f29b9c9e39d3ac16e441f5c236ad0767cd0)
fix GC bug

GC during allocation of a pair, weak box, ephemeron, or
weak array went wrong if the GC-notification callback
allocated any of those kinds of things.

(Bug found by running tests in GC-stress mode.)
(cherry picked from commit 49fbca5b1830bc4bddb8522d7647518227a32dd0)
Terminate typechecking on cyclic lists.

Closes PR 13687.
(cherry picked from commit b8ab1334d9192720ebb6a37e311880f158276d8b)
Add `#:omit-define-syntaxes` to `define-type`.
(cherry picked from commit ecf02a32b4e2431e57f77da4f497fcb8f62426ec)
Correctly protect Procedures in TR.

Closes PR 13664.
(cherry picked from commit fc36c12ce4df96cca4df053fa5e0f4c4969b7e8a)
Add polydots to all things that support it.

Closes PR 13612.
Closes PR 13584.
(cherry picked from commit 2e2ef0b57aa5ca5c87d86e035e633cd265f94d9f)
Small TR fixes.
(cherry picked from commit a94c449ff1d7e6eb299c06d8be2da681d1b99d9f)
Use information of application site, to reduce possible arities.

Closes PR12905.
(cherry picked from commit 55aba088decf0c243a7d5d0cf912e03efc524d40)
Don't let map introduce type variables.

Closes PR 13581.
(cherry picked from commit 67dd956b6acf5533cd2551cac7fd618eca839261)
Fix expected type when typechecking map
(cherry picked from commit 863ac053328b0df54cc10a0724274f7d110d6d49)
Fix subtyping of (ListDots t 'a) <: (Listof t).

Closes PR 13636.
(cherry picked from commit 6898a7c880f1a37219e61d420ed6610a4d24f384)
Switch out? to from-typed? as it has the same meaning.
(cherry picked from commit 03e1ffda3e1c27c982b6ed4681d7d1bc2037b643)
Allow requiring functions with filters in contravariant positions.
(cherry picked from commit dbcb1414dadd6fb125b5527d9b0d8853dd1ce616)
Make type->contract correctly respect variance.

Track whether we are protecting values from the typed side and/or the
untyped side.

Closes PR 13662.
Closes PR 13663.
Closes PR 13665.
(cherry picked from commit b5b13222c8eaf7e2152b77ab21d21568103c55c8)
Allow read-only hash operations to accept HashTop.

Closes PR13710.
(cherry picked from commit e6ff57f3bda3f7521722351ed8c3a799d6b99464)
Document VectorTop and HashTableTop.
(cherry picked from commit 457ca0982f941372409dec2c03ed46ca9847a097)
Cleanup names-of-struct
(cherry picked from commit 154ab046fe58bf15c7cc6eb5e2a4671d07edea14)