add langselect
grub2: remove resetGfxmodeIfNeed()
grub2: fix config issue in Setup()
grub2: add fixSettingDistro()
grub2: sort settting lines before saving, and update test code
grub2: add test code, TestParseInvalidSettings() and TestFixSettings()
grub2: refactor code, add doSetXXX() and doGetXXX()
grub2: refactor code, create grub object in each test case
grub2: fix parseGfxmode() issue, and add test code
grub2: fix theme.regenerateBackgroundIfNeed(), use gfxmode in config
grub2: refactor code, split setters to make write test code easily
grub2: refactor code, split fixSettings() to facilitate testing
grub2: rewrite logic code about default entry and timeout, and add related test code
grub2: add test code for Setup()
grub2: add test code TestFixSettingDefaultEntry()
grub2: fix setPropEnableTheme() issue