Currently does not get the modules in a way that they can be downcasted
to test if StatusMonitor, etc

Correctly navigate to parent module via virtual path.

If someone includes the Logger into an ApplcationModule and calls writeAll() the Logger variable message will be written. To catch that cases set message empty after calling sendMessage and ignore empty messages in the LoggingModule.

    - Basic structure of test application
    - Added modules
    - Refactoring of StatusMonitor to provide a non-templated base class
    - Needs follow-up, for status see issue #14 and the linked follow-up
      ticket

- ConfigReader is in ApplicationCore.h, but was including ApplicationCore.h itself
- Added include guards to ApplicationCore.h, although it's not stricktly needed (all included headers have one). Might speed up complilation because it makes it easier for the parser.

Connecting a device only works if the PVs are readonly! So one has to
use the logical name mapping backend. This also allows to select only a
subset of the device PV to be added to the history module.

I observed that, after reading the message sometimes the log level was
wrong. Most likely because it was updated after the message was read.
Now the log level is bound to the message. This also reduces the number
ctk variables.

It is suffiecient to have the message being push type.
readAny of the ReadAnyGroup will update poll type variable
automatical once there was an update of the push type message.

Some custom tags from private servers have been removed.
Added "CS" tag, which allows to use findTag on the Logging module
and connect it directly to the control system.

the swicth because order is not important for these.

ModuleList serves as a container for VariableGroups. The VariableGroups
mirror xml modules in the config file.

Xml parsing logic factored out to class ConfigParser.

Unfortunatly this currently breaks the ServerHistory module, as it relies on slashes in accessor names. The MicroDAQ module had the same issue but has already been fixed. This fix can be adopted to the ServerHistory module as well.

Now one can add ScalarOutput and ArrayOutput variables to the history modules by using tags.

This is still not nice. Now for every data type an individual module needs to be created.

- Make data decimation configurable
- Addded some documentation
- Some code cleaning (eliminate warnings, move internal classes into detail namespace)