Parent can be any instance of Wx::Window

# TODO make a base class for Dict::Learn frames (e.g. Dict::Learn::Frame::Base or something like this)
Add an initial version of a test for Dict::Learn::Widget::Sidebar
Shouldn't be lazy but should be Int
Add an initial version of a test for Dict::Learn::Frame::IrregularVerbsTest
Let them be lazy
They can be any instance of Wx::Window

# TODO make a base class for frames
Add an initial version of the test for Dict::Learn::Frame::TranslationTest::Result
Add an initial version of the test for Dict::Learn::Frame::IrregularVerbsTest::Result
Need to include Wx::Html for Wx::SimpleHtmlListBox
Rename Dict::Learn::Combo::WordList as Dict::Learn::Widget::WordList
Add an initial version of the test for Dict::Learn::Widget::WordList
If word already exists, show the number of its translations
Remove commented out code