Using Core's ESP8266WebServer + some additional handlers.
Includes barebones page, without authorization.

Allows to explicitly set OTA_WEB_SUPPORT=1 with the ESPURNA_CORE and still get a web page.
Around the same size as ArduinoOTA + MDNS, so it might also be a good
suggestion to disable those when web support is enabled.

Remove AXTLS mentions from asynctcp and httpupdate
More namespace MODULE and namespace { ... }

Don't depend on the ArduinoOTA to do this.
Also fixes addService using nullptr as a name, since the hostname was never set.

- general conversion from .ino modules into a separate .cpp files
- clean-up internal headers, place libraries into .h. guard .cpp with _SUPPORT flags 
- fix some instances of shared variables instead of public methods
- tweak build system to still build a single source file via os environment variable ESPURNA_BUILD_SINGLE_SOURCE

* Config: remove prototypes.h

* fixup order

* word

* add missing

* fix warning while still using .ino

* bad at c/p;

* Test: check core feature build

* order

* add missing

- add httpupdate ota impelementation
- move async ota into a separate module
- support bearssl & axtls through wificlientsecure
- allow to disable arduino ide ota module