Rename proguard.cfg to proguard-project.txt

to align with Android Tools defaults.
transport-xmpp: Allow proguard debug builds

by adding custom_rules.xml with a workaround for proguard debug builds.
MAXS Pre-Release 0.0.1.11
transport-xmpp: enabled proguard

and split proguard cfg in a component and shared part.
homepage: Make it clear that MAXS is GPLv3 licensed
transport-xmpp: proguard: keep more classes
transport-xmpp: Add custom -obfuscate target

This is a slightly modified version of the '-obfuscate' target of
$ANDROID_HOME/tools/ant/build.xml that only calls proguard if it's
actually needed.
homepage: add xmpp.net public server directory
Make service intents explicit

Dianne noted in frameworks/base/221ea892dcc661bd07d6f36ff012edca2c48aed4
[1] and frameworks/base/fd6c7b12c312bef3ab9de2a8fcdeef9260fd85f1 that
"Implicit intents with startService are not safe". This is because the
behavior of implicit intents with multiple matching services is
undefined.

[1] https://android.googlesource.com/platform/frameworks/base/+/221ea892dcc661bd07d6f36ff012edca2c48aed4
custom_rules.xml: Avoid faulty builds without proguard

Always setting 'out.dex.jar.input.ref' empty resulted in faulty builds
when proguard.enabled is *not* set. We now hook into -pre-build and do
the right thing™.
MAXS Release 0.0.1.11
MAXS Pre-Release 0.0.1.12
transport-xmpp: re-enable proguard
custom_rules.xml: indent -prebuild-target
ProGuard: Allow enabling/disabled just via proguard.config

Like it would be with a plain SDK build.xml. We don't need to set
proguard.enabled explicitly.
homepage: Minor documentation changes
transport-xmpp: Change custom_rules.xml project name

to avoid

Duplicated project name in import. Project android_rules defined first
in custom_rules.xml and again in $ANDROID_HOME/tools/ant/build.xml
transport-shared: Add missing Sms.Types to avoid ISE
Log: Only log debug messages if enabled or settings not set