Revert "Add ability to skip display of submenus"

This reverts commit 13264a7c8bb820a2080d34ece56c31bcdf42a678.
Revert "CSS: Remove uppercase transform on menu headings"

This reverts commit c1feb96ab3ee8ad7e6e4a7f1a0d986b763510ef3.
Revert "Move menu generation functionality into Menu Class and update CSS"

This commit was merged without approval or review from the team, and
introduced several regressions and issues, documented in

- Issue #17712: errors in menu and submenu display
- Issue #17779: New Menu Class is breaking plugins

See also issue #17711 and comments in pull request #316.

This reverts commit 29c2f8211de8869b3b1b072467b54252d0db5024.
Fix breaks after merge. One temp fix in columns_api.php.
Merge branch 'master' of https://github.com/mantisbt/mantisbt into modern-ui-2

Conflicts:
	account_prefs_inc.php
	account_prof_edit_page.php
	account_prof_menu_page.php
	account_sponsor_page.php
	core/authentication_api.php
	core/html_api.php
	css/default.css
	manage_columns_inc.php
	manage_overview_page.php
	manage_proj_cat_edit_page.php
	manage_proj_edit_page.php
	manage_proj_page.php
	manage_proj_ver_edit_page.php
	manage_tags_page.php
	manage_user_create_page.php
	manage_user_edit_page.php
	plugins/MantisGraph/pages/summary_graph_imp_category.php
	plugins/MantisGraph/pages/summary_graph_imp_resolution.php
	plugins/MantisGraph/pages/summary_graph_imp_status.php
	plugins/MantisGraph/pages/summary_jpgraph_page.php
	plugins/XmlImportExport/pages/import_action.php
	proj_doc_add_page.php
	proj_doc_edit_page.php
	proj_doc_page.php
	summary_page.php
Fix reauth page footer after merge.