Implemented Find-Replace Overlay.

In response to issue eclipse-platform#1090. Goals for this overlay are a simple
and modern UI/UX for finding/replacing in eclipse.

!!!!!
This commit is only a functional commit meant to showcase a new feature.
The code still has several flaws and needs a lot of improvement and
redesign before being considered for Merging.
!!!!!

-- [Modern Find/Replace] Refactor FindReplaceDialog

The FindReplaceDialog's business-logic is now handled in the
FindReplacer.
The FindReplacer communicates using a FindReplaceStatus object which is
polled by FindReplaceDialog as needed and allows for displaying correct
messages in the Interface.

This Refactoring is required so that the business-logic can be reused in
the new FindReplace overlay, as proposed in issue eclipse-platform#1090

Author: Maximilian Wittmer

bundles/org.eclipse.jface.text/META-INF/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.jface.text
-Bundle-Version: 3.24.200.qualifier
+Bundle-Version: 3.25.0.qualifier
 Bundle-Vendor: %providerName
 Bundle-Localization: plugin
 Export-Package: 

bundles/org.eclipse.ui.workbench.texteditor/META-INF/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.ui.workbench.texteditor; singleton:=true
-Bundle-Version: 3.17.200.qualifier
+Bundle-Version: 3.18.0.qualifier
 Bundle-Activator: org.eclipse.ui.internal.texteditor.TextEditorPlugin
 Bundle-ActivationPolicy: lazy
 Bundle-Vendor: %providerName