add new configuration classes

Prepare refactoring with new class structure.
fix minor bug

* FIX: error toolbar did not work properly
complete configuration category 'general'

- complete ConfigurationGeneral
- new classes for Gender and HeartRateUnit
- fix all usages of CONF_… of general values
complete configuration category 'general'
complete configuration category 'activity view'
revert changes and refactor again

* ADD: new class 'Parameter'
 - this class is for general parameter, e.g. Int, Bool, Select, …
 - this class is not connected to the database and configuration

* ADD: new class 'ConfigurationHandle'
 - this class connects a parameter and a key
 - the configuration class is now based on these handles

In addition, none of these classes holds the information for the
configuration window. Therefore another class will be needed.
complete configuration category 'privacy'
complete configuration category 'activity form'
complete configuration category 'data browser'
complete configuration category 'design'
complete configuration category 'vdot'
complete configuration category 'trimp'
complete configuration category 'misc'
complete configuration category 'activity view'

Add missing values to category.

Within this:
 - remove 'show'-flags for plots
 - remove some other unused values
complete configuration category 'data'

Within these changes:
 - allow configuration handle to keep track of all 'ParameterSelectRow'
 - remove 'CONF_…' definitions from unit tests
refactor configuration updates

Use new methods to update configuration methods and add some bug fixes.
refactor configuration window

Each category creates now its own fieldset.

Additional bug fixes (caused by previous commits):
 - type in trimp class
 - reload flags for data browser / training did not work
 - reload data browser did not work twice
remove old config classes

Remove old classes and complete refactoring.

Within this: fixes #1116.
rename some config values
Merge branch 'feature/refactor-config'

Refactor configuration structure:
 - Instead of using constants (`CONF_...`) we're now using the static
class `Configuration::...`.
 - There are new `Parameter` classes for all kind of parameters (bool,
int, array, select, ...). They are extended to e.g. `Gender`,
`HeartRateUnit`, `ElevationMethod`, and so on.

These commits include some minor bugfixes.