merge

* itertools: added `closest` to find ordered minimal/maximal values of an array

* removed bridging function now available in LLVM 12.0.1

* do not scope hidden inlines

* ensure inlines always have a scope

* `from ... let` now recognizes renaming symbols during import using `(newname = sourcename)`

Map: fix key lookup failing when keys are "the same" (equivalent value, coerced from different storage) but hash differently.

* updated hgignore

* renamed internal string type to `string` to reduce confusion

* check-in so generation example

* added `static-try` sugar and `static-try-closure` spice

merge

* updated IRC channel information

* replaced special aarch64 dependencies with native target

* better tagging

* `glsl`: added `gl_PrimitiveID`
* SPIR-V: fixed `PrimitiveId` depending on raytracingNV rather than geometry capability

* support for hashing `Value`

* better tagging

* `Map`: added copy operator

* added `trap` and `debugtrap` intrinsics