tweaks after 2.5 prod update

Conflicts:
	theme/zebra
new pictures for @bunderwood theming
fixing course overview drop-down width & h2 font size
add login button to clean theme nav bar
adding custom logo to header navigation - clean theme only
new header logo affix to site root, add favicon
fix 2.7 relative urls for login button and header logo.
new feature: custom-forgotpassword -- updating text on forgot password page (lang/en/moodle.php)
Redirect to custom homepage. Closes #9.
redirect to custom homepage for all devices
MDL-46652 custom_menu: fix for multi-language support breaks menu nesting

Fixed bug by building full menu structure, then removing hidden menu items and all associated children.
Refactored custom_menu_item class and convert_text_to_menu_nodes() to improve maintenance.
open in new tab for external links

Conflicts:
	lib/outputcomponents.php
force login for my page
instantiate custom_menu even if settings are empty
show custom menu items by capability permissions
Merged Experience SES SSO feature. Closes #13
Added open courses redirect. Closes #10
Merge course dropdown. Closes #8.
cherry-pick 6fb6597b05. Reworked my moodle semester feature.
cherry-pick 2f47183085. Fix: single_select and array_key_exists.