Make missing identifiers and classes in plugin.xml errors

Subsequent commits fix the errors

Author: jonahgraham

terminal/plugins/org.eclipse.tm.terminal.control/.settings/org.eclipse.pde.prefs

@@ -12,6 +12,7 @@ compilers.p.build.source.library=1
 compilers.p.build.src.includes=1
 compilers.p.deprecated=1
 compilers.p.discouraged-class=1
+compilers.p.exec-env-too-low=1
 compilers.p.internal=1
 compilers.p.missing-packages=2
 compilers.p.missing-version-export-package=2
@@ -22,10 +23,10 @@ compilers.p.no.automatic.module=1
 compilers.p.not-externalized-att=1
 compilers.p.service.component.without.lazyactivation=1
 compilers.p.unknown-attribute=1
-compilers.p.unknown-class=1
+compilers.p.unknown-class=0
 compilers.p.unknown-element=1
-compilers.p.unknown-identifier=1
-compilers.p.unknown-resource=1
+compilers.p.unknown-identifier=0
+compilers.p.unknown-resource=0
 compilers.p.unresolved-ex-points=0
 compilers.p.unresolved-import=0
 compilers.s.create-docs=false