update readme; remove outdated compile information; new donation information

README.md

@@ -91,23 +91,9 @@ Google [Play Store](https://play.google.com/store/apps/details?id=eu.siacs.conve
 
 Buying the App from the Play Store will also give you access to our [beta test](#beta).
 
-#### I don't have a Google Account but I would still like to make a contribution
+#### I don't have a Google Account but I would still like to make a donation
 
-I accept donations over PayPal, bank transfer and various crypto currencies. For donations via PayPal use the button below:
-
-[![Donate with PayPal](https://www.paypalobjects.com/en_US/i/btn/btn_donate_LG.gif)](https://www.paypal.me/ConversationsIM)
-
-**Disclaimer:** I'm not a huge fan of PayPal and their business policies. For
-larger contributions please get in touch with me beforehand and we can talk
-about bank transfer (SEPA).
-
-##### Crypto currencies
-
-Bitcoin: `3KAD8vew6tPZDjiUJNnZ3YUoUxrCEVNwFL`
-
-Bitcoin Cash: `16ABkXzYAwWz8Y5DcWFfbBRqL63g3hzEaU`
-
-Ether: `0x5c4e5239cd9c6f4a909e4e8361526e2e3c8ba9fa`
+I’m listing several options to support me financially on [my website](https://gultsch.de/donate.html). Among other things [Liberapay](https://liberapay.com/iNPUTmice/donate), [GitHub Sponsors](https://github.com/sponsors/inputmice) and bank transfer.
 
 #### How do I create an account?
 XMPP, like email, is a federated protocol, which means that there is not one company you can create an *official XMPP account* with. Instead there are hundreds, or even thousands, of providers out there. One of those providers is our very own [conversations.im](https://account.conversations.im). If you don’t like to use *conversations.im* use a web search engine of your choice to find another provider. Or maybe your university has one. Or you can run your own. Or ask a friend to run one. Once you've found one, you can use Conversations to create an account. Just select *register new account* on server within the create account dialog.
@@ -387,7 +373,7 @@ There are XMPP Clients available for all major platforms.
 #### Windows / Linux
 For your desktop computer we recommend that you use [Gajim](https://gajim.org). You need to install the plugins `OMEMO`, `HTTP Upload` and `URL image preview` to get the best compatibility with Conversations. Plugins can be installed from within the app.
 #### iOS
-Unfortunately we don‘t have a recommendation for iPhones right now. There are two clients available [ChatSecure](https://chatsecure.org/) and [Monal](https://monal.im/). Both with their own pros and cons.
+Unfortunately we don‘t have a recommendation for iPhones right now. There are three clients available [Siskin](https://siskin.im/), [ChatSecure](https://chatsecure.org/) and [Monal](https://monal.im/). Each with their own pros and cons.
 
 
 ### Development
@@ -416,25 +402,6 @@ There are two build flavors available. *free* and *playstore*. Unless you know w
 
 [![Build Status](https://travis-ci.org/inputmice/Conversations.svg?branch=development)](https://travis-ci.org/inputmice/Conversations)
 
-#### How do I update/add external libraries?
-
-If the library you want to update is in Maven Central or JCenter (or has its own
-Maven repo), add it or update its version in `build.gradle`. If the library is
-in the `libs/` directory, you can update it using a subtree merge by doing the
-following (using `minidns` as an example):
-
-    git remote add minidns https://github.com/rtreffer/minidns.git
-    git fetch minidns
-    git merge -s subtree minidns master
-
-To add a new dependency to the `libs/` directory (replacing "name", "branch" and
-"url" as necessary):
-
-    git remote add name url
-    git merge -s ours --no-commit name/branch
-    git read-tree --prefix=libs/name -u name/branch
-    git commit -m "Subtree merged in name"
-
 #### How do I debug Conversations
 
 If something goes wrong Conversations usually exposes very little information in