add PreferenceFragment lib since appcompat lacks such a thing

Although Google is encouraging people to make old devices run apps
with the action bar (via appcompat-v7), they haven't provided a way
for people to create preference/setting screens with an action bar.

There are plenty of issues in the Android issue tracker relating
to this, but it doesn't yet seem to be on the radar of the Android
devs.

Until there is a native implementation of PreferenceFragment in
the appcompat-v7 support library, this submodule provides is a 3rd
party solution. It is actually a fork of the first repo in github,
though that was a bit of an upload and dump, without accepting MR's.
This fork includes gradle support.

.gitmodules

@@ -34,6 +34,10 @@
 	path = extern/nanohttpd
 	url = https://github.com/eighthave/nanohttpd
 	ignore = dirty
+[submodule "extern/android-support-v4-preferencefragment"]
+	path = extern/android-support-v4-preferencefragment
+	url = https://github.com/CyberEagle/android-support-v4-preferencefragment.git
+	ignore = dirty
 [submodule "extern/zxing-core"]
 	path = extern/zxing-core
 	url = https://gitlab.com/fdroid/zxing-core.git

build.gradle

@@ -27,6 +27,9 @@ dependencies {
 	compile project(':extern:jmdns')
 	compile project(':extern:zipsigner')
 	compile project(':extern:zxing-core')
+	compile( project(':extern:android-support-v4-preferencefragment') ) {
+		exclude module: 'support-v4'
+	}
 }
 
 project(':extern:UniversalImageLoader:library') {

extern/android-support-v4-preferencefragment

@@ -0,0 +1 @@
+Subproject commit fab3cf8a0699a5ba45b66d4dcddcf7947239de9b

settings.gradle

@@ -10,6 +10,7 @@ include ':extern:spongycastle:pg'
 include ':extern:spongycastle:pkix'
 include ':extern:spongycastle:prov'
 include ':extern:zxing-core'
+include ':extern:android-support-v4-preferencefragment'
 
 include ':support-v4'
 project(':support-v4').projectDir = new File('extern/Support/v4')