fixed an indent.
fixed an indent.
fixed indents.
added basic files to implement a feture that performs user defined action triggered by events.
added basic framework to perform used defined action.

Note: many of functions are not implemented yet or stub.
added a utility class for tests.
add a test program used for the test of ActionManager mechanism.
added a part of test for ActionManager.
added a test for ActionManager::makeExecArg().
added a test for ActionManager::makeExecArgs() with two argsments.
added a helper function for test_makeExecArg and the families.
added code to drop the empty string in the argument list.

This condition typically happens when the command line has spaces
at the tail.
added a file path the function failed to create in an error message.
added assertions for the result of the function for pipe creation.
fixed the bug that makes pipe files with the same name.
added comments.
added a utility class: TimeCounter.
added functions to send/receive data via pipe.
added assertions for the arguments passed to the child process executed by ActionManager::execCommandAction().
added stub functions to start and stop thread to collect exited child processes.