usercore: remove unused class TestTask
uicore: remove useless needForceUpdate method in UICore class

also fixes clang static-analyzer warning "This statement is never executed"
usercore/ToolManager: remove unused variable in startDownload

also fixes clag static analyzer warning "Value stored to 'bIsDownloading' is never read"
ipc_pipe/IPCPipeBase: remove unused function "print_buffer"

also fixes clang static analyzer warning "This statement is never executed"
Merge pull request #596 from karolherbst/clang-static-analyzer

some unused stuff I found while going through clangs static analyzer issues