* pyz: yeet the resource tar which is now pointless thanks to pkgres
* cache impresource stuff because pyz lookups are Extremely slow
* prefer tx_file when possible for slightly better performance
* use hardcoded list of expected resources instead of dynamic
discovery at runtime; much simpler and probably safer
* fix some forgotten resources (copying.txt, insecure.pem)
* fix loading jinja templates on windows
add support for reading webdeps and jinja-templates using either
importlib_resources or pkg_resources, which removes the need for
extracting these to a temporary folder on the filesystem
* util: add helper functions to abstract embedded resource access
* http*: serve embedded resources through resource abstraction
* main: check webdeps through resource abstraction
* httpconn: remove unused method `respath(name)`
* use __package__ to find package resources
* util: use importlib_resources backport if available
* pass E.pkg as module object for importlib_resources compatibility
* util: add pkg_resources compatibility to resource abstraction
* error-message which explains how to run on py2 / older py3
when trying to run from source
* check compatibility between jinja2 and cpython on startup
* verify that webdeps are present on startup
* verify that webdeps are present when building sfx
* make-sfx.sh grabs the strip-hints dependency