Move correction bar to Main activity

Signed-off-by: Janusz Kozerski <janusz.kozerski@gmail.com>
Minor fixes

* Move declaration of UI objects (buttons, etc.) from method body to
      class declaration - as a private class members.
* Rename private class members for more informative names.

Signed-off-by: Janusz Kozerski <janusz.kozerski@gmail.com>
Add info about correction value next to correction bar

Signed-off-by: Janusz Kozerski <janusz.kozerski@gmail.com>