Moved Category.java into its own new subpackage of data

...cz/muni/fi/pv168/project/data/TemporaryValueProvider.java

...java/cz/muni/fi/pv168/project/data/category/Category.java

src/main/java/cz/muni/fi/pv168/project/data/task/Task.java

...ava/cz/muni/fi/pv168/project/db/category/CategoryDao.java

.../fi/pv168/project/model/CategoryStatisticsTableModel.java

...va/cz/muni/fi/pv168/project/ui/dialog/CategoryDialog.java

...n/java/cz/muni/fi/pv168/project/ui/dialog/TaskDialog.java

...v168/project/ui/dialog/factory/CategoryDialogFactory.java

...ject/ui/dialog/factory/ExistingCategoryDialogFactory.java

...fi/pv168/project/ui/dialog/factory/TaskDialogFactory.java

...project/ui/main/panel/listholder/CategoryHolderPanel.java

...pv168/project/ui/main/view/CategoryAndStatisticsView.java

...a/cz/muni/fi/pv168/project/ui/main/view/CategoryView.java

...cz/muni/fi/pv168/project/ui/main/view/StatisticsView.java

...ct/ui/renderer/statistics/CategoryStatisticsRenderer.java