Add class for menubar

This class is added so that the MainWindow class is less cluttered with
irrelevant statements.
Let WordSelector class manage the current mode and minimun num of letters

This change is made so that an instance of WordSelector can be passed to the
MenuBar class and have the mode changed within it, instead of passing the
whole (reference of) TypePanel class.
Pass WordSelector instance to MenuBar class

This change is made so that MenuBar can change the mode directly.
Change size of RecordsWindow to match the size of MainWindow

The size needs to be increased because menubar has been added to the
MainWindow.
Implement changing modes
Merge branch 'modes' into menu

Changing modes feature is implemented.
Fix issue where exception occurs when pressing cancel when selecting color

This issue is caused because when pressing cancel, null is returned from the
ColorSelector, invoking a NullPointerException.
Rename "Practice Mode" menu to "Mode"

Unnecessary menu item "Change Practice Mode" in "Settings" menu is also
removed.
Remove unnecessary menu item

This menu item is not needed because there is already a separate menu for
changing modes.
Add feature to change the font by using JFontChooser
Pass null to JFontChooser when showing dialog
Use dispose() instead of setVisible(false) in ColorSelector class
Return a list of all keyboard layouts instead of a comma-separated list

The name of the method is also changed to a more intuitive name.
Add feature to change keyboard layout

However, updating the database is not working. Thus, preferences are reset
after closing and reopening the program.
Fix issue where keyboard layout String is unintetionally modified

This happens when cancel is pressed when changing the keyboard layout. This
issue is solved by using the split() method of String class.
ArrayIndexOutOfBoundsException is not expected because QWERTY is always an
entry. However, caution needs to be taken when implementing a feature to allow
removal of keyboard layouts.
Update database after changing the font

However, the update() method is not working, so the change is currently not
saved.
Merge branch 'menu' into prototype

The menubar has been implemented.