Adblock Support for Embeds (#308)

Fixes #307 

- Adds optional adblock support, via wabac.js (dependent on
webrecorder/wabac.js#167).
- For now, adblock enabled only for embeds via the `useAdblock`
attribute, and can be enabled per archived item.
- By default, adblock filter rules from
[EasyList](https://easylist.to/easylist/easylist.txt) are used, however,
a custom filter rules file can be used via `adblockRulesUrl` attribute
(default is ./adblock/adblock.gz)
- Added `fetch-adblock.sh` script to fetch latest easylist, filter out
`##` rules and compress to `./adblock/adblock.gz`
- Not yet possible to enable adblock for standalone browsing via
replayweb.page
- bumps version to 2.0.0-beta.3

mkdocs/site/docs/embedding/index.md

@@ -151,6 +151,8 @@ The `#!html <replay-web-page>` tag is a web component that supports a number of
 | `requireSubdomainIframe` | If set, will only load embed in an iframe loaded from a subdomain, for increased origin isolation. |
 | `loading="eager"` | If set, will load the entire WACZ file at once (regardless of size), and not attempt on-demand range request loading. |
 | `useRuffle` | If set, will enable include Ruffle Flash emulator. Must include the `ruffle/` directory in `replayBase`. |
+| `useAdblock` | If set, will enable adblocking, by injecting CSS stylesheets to hide ads based on a list of ad filter rules.  By default, the [EasyList](https://easylist.to/) filter rules are used. |
+| `adblockRulesUrl` | Provide a URL to a custom [Adblock Plus filter rules](https://adblockplus.org/filters) formatted text file. Note that only rules containing CSS selectors (via `##` filter) are used, other lines in the rules list are ignored. |
 
 ## Further Examples
 

mkdocs/sitefiles.txt

@@ -5,3 +5,4 @@ embed.html
 webmanifest.json
 favicons
 ruffle
+adblock