Improved plugin imports to address issues with Eclipse 2018-09

In comparison to Neon, 2018-09 seems to be more picky about which dependencies are explicitly declared in the manifests. This commit adds the missing explicit dependencies and thus makes Capra buildable on Eclipse 2018-09 (with a specific target definition).
diff --git a/org.eclipse.capra.generic.priority/META-INF/MANIFEST.MF b/org.eclipse.capra.generic.priority/META-INF/MANIFEST.MF
index 0ca4de3..4416df4 100644
--- a/org.eclipse.capra.generic.priority/META-INF/MANIFEST.MF
+++ b/org.eclipse.capra.generic.priority/META-INF/MANIFEST.MF
@@ -5,5 +5,4 @@
 Bundle-Version: 0.7.0.qualifier
 Require-Bundle: org.eclipse.capra.core
 Bundle-RequiredExecutionEnvironment: JavaSE-1.8
-Import-Package: org.eclipse.mylyn.builds.internal.core
 Bundle-Vendor: Capra Development Team
diff --git a/org.eclipse.capra.testsuite/META-INF/MANIFEST.MF b/org.eclipse.capra.testsuite/META-INF/MANIFEST.MF
index 3c98fb2..8e49c46 100644
--- a/org.eclipse.capra.testsuite/META-INF/MANIFEST.MF
+++ b/org.eclipse.capra.testsuite/META-INF/MANIFEST.MF
@@ -7,16 +7,24 @@
 Require-Bundle: org.junit,
  org.eclipse.equinox.registry,
  org.eclipse.core.resources,
- org.eclipse.jdt.core,
- org.eclipse.jdt.launching,
- org.eclipse.emf.ecore,
- org.eclipse.ui.workbench,
- org.eclipse.capra.ui,
- org.eclipse.cdt.core,
- org.eclipse.capra.generic.tracemodels,
- org.eclipse.capra.generic.priority,
  org.eclipse.core.runtime,
  org.eclipse.core.commands,
+ org.eclipse.core.filesystem,
+ org.eclipse.emf.edit,
+ org.eclipse.emf.ecore,
+ org.eclipse.emf.ecore.editor,
+ org.eclipse.ui.workbench,
+ org.eclipse.ui.ide,
+ org.eclipse.cdt.core,
+ org.eclipse.cdt.managedbuilder.core,
+ org.eclipse.jdt.core,
+ org.eclipse.jdt.launching,
+ org.eclipse.jface,
+ org.eclipse.osgi,
+ org.eclipse.swt,
+ org.eclipse.capra.generic.artifactmodel,
+ org.eclipse.capra.generic.tracemodels,
+ org.eclipse.capra.generic.priority,
  org.eclipse.capra.core,
  org.eclipse.capra.ui.plantuml,
  org.eclipse.capra.handler.jdt,
@@ -25,13 +33,8 @@
  org.eclipse.capra.handler.emf,
  org.eclipse.capra.generic.persistence,
  org.eclipse.capra.handler.file,
- org.eclipse.cdt.managedbuilder.core,
- org.eclipse.capra.ui.notification,
- org.eclipse.ui.ide,
- org.eclipse.core.filesystem,
- org.eclipse.emf.edit,
- org.eclipse.emf.ecore.editor,
- org.eclipse.capra.generic.artifactmodel
+ org.eclipse.capra.ui,
+ org.eclipse.capra.ui.notification
 Bundle-RequiredExecutionEnvironment: JavaSE-1.8
 Import-Package: org.eclipse.swt.dnd
 Bundle-Vendor: Capra Development Team
diff --git a/org.eclipse.capra.ui.zest/META-INF/MANIFEST.MF b/org.eclipse.capra.ui.zest/META-INF/MANIFEST.MF
index 827bb9d..b7083b3 100644
--- a/org.eclipse.capra.ui.zest/META-INF/MANIFEST.MF
+++ b/org.eclipse.capra.ui.zest/META-INF/MANIFEST.MF
@@ -4,10 +4,10 @@
 Bundle-SymbolicName: org.eclipse.capra.ui.zest;singleton:=true
 Bundle-Version: 0.7.0.qualifier
 Require-Bundle: org.eclipse.ui,
+ org.eclipse.core.runtime,
  org.eclipse.capra.core,
  com.google.inject,
  org.eclipse.gef4.zest.fx.jface,
- org.eclipse.zest.layouts,
  org.eclipse.capra.ui,
  org.eclipse.gef4.layout,
  org.eclipse.gef4.mvc.fx,
@@ -17,4 +17,3 @@
  org.eclipse.gef4.common
 Bundle-RequiredExecutionEnvironment: JavaSE-1.8
 Bundle-Vendor: %Bundle-Vendor
-Import-Package: javafx.scene.input