CodeCompletionWorker refactored

[Niko Sams]

> Looks ok. If C++ code-completion still works, commit it(Also try
> cppcodecompletiontest).
great, thanks.

one cppcodecompletiontest test fails for me - event without the patch - is
this just me?

Niko

/cppcodecompletiontest testInheritanceVisibility
<unknown program name>(15889)/ KDevelop::allocateRepository: picked
duchain directory "/home/niko/.kdevduchain/1"
qExec: argc 2
argc 2
argument testInheritanceVisibility
********* Start testing of TestCppCodeCompletion *********
Config: Using QTest library 4.4.3, Qt 4.4.3
PASS   : TestCppCodeCompletion::initTestCase()
QDEBUG : TestCppCodeCompletion::testInheritanceVisibility() <unknown
program name>(15889)/?[0;34m ContextBuilder::buildContexts?[0m:
ContextBuilder::buildContexts: compiling
QDEBUG : TestCppCodeCompletion::testInheritanceVisibility() <unknown
program name>(15889)/?[0;34m ContextBuilder::buildContexts?[0m: built
top-level context with 4 declarations and 0 included files
QDEBUG : TestCppCodeCompletion::testInheritanceVisibility() <unknown
program name>(15889)/?[0;34m
Cpp::CodeCompletionContext::CodeCompletionContext?[0m: local class:
"B"
QDEBUG : TestCppCodeCompletion::testInheritanceVisibility() <unknown
program name>(15889)/?[0;34m
Cpp::CodeCompletionContext::CodeCompletionContext?[0m: local class:
"B"
FAIL!  : TestCppCodeCompletion::testInheritanceVisibility() Compared
QStringLists have different sizes.
   Actual (CompletionItemTester(top, "B::").names) size  : '2'
   Expected (QStringList() << "BMyClass") size: '1'
   Loc: [/home/niko/kde/kdevelop-stable/plugins/languages/cpp/tests/test_cppcodecompletion.cpp(258)]
PASS   : TestCppCodeCompletion::cleanupTestCase()
Totals: 2 passed, 1 failed, 0 skipped
********* Finished testing of TestCppCodeCompletion *********