Remove uses of deprectated Eclipse API and warnings

[basti1302]

• /de.bastiankrol.startexplorer/META-INF/MANIFEST.MF: No required execution environment has been set
• /de.bastiankrol.startexplorer/META-INF/MANIFEST.MF: The 'Eclipse-LazyStart' header is deprecated, use 'Bundle-ActivationPolicy'
• /de.bastiankrol.startexplorer/src/de/bastiankrol/startexplorer/preferences/AbstractStartExplorerPreferencePage.java: The method savePluginPreferences() from the type Plugin is deprecated

[genodeftest]

Hi
for the first one:
startexplorer is developed for Java SE 6. If you set the Java Runtime in 'de.bastiankrol.startexplorer → Properties → Build path → Libraries' to JavaSE-1.6, startexplorer will compile without warnings. Setting it to J2SE-1.5 generates compile errors since some code uses features introduced in Java 6.
Btw: I recommend setting the Java Runtime in Build path to prevent bugs caused by accidential use of Java 7/8 specific features.

For the second one: the fix is simple, just replace one line with another.

The diff:

diff --git a/plugin/META-INF/MANIFEST.MF b/plugin/META-INF/MANIFEST.MF
index c2a6c54..7c25563 100644
--- a/plugin/META-INF/MANIFEST.MF
+++ b/plugin/META-INF/MANIFEST.MF
@@ -1,5 +1,6 @@
 Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
+Bundle-RequiredExecutionEnvironment: JavaSE-1.6
 Bundle-Name: Startexplorer Plug-in
 Bundle-SymbolicName: de.bastiankrol.startexplorer; singleton:=true
 Bundle-Version: 1.4.1.qualifier
@@ -12,6 +13,6 @@ Require-Bundle: org.eclipse.ui,
  org.eclipse.core.expressions,
  org.eclipse.ui.ide,
  org.eclipse.core.variables
-Eclipse-LazyStart: true
+Bundle-ActivationPolicy: lazy
 Bundle-ClassPath: lib/json-simple-1.1.1.jar,
  .

[basti1302]

Changed MANIFEST.MF according to your suggestions in branch master.