MDL-43135 Guest Enrol: new language string for with key icon

AMOS BEGIN
CPY [pluginname,enrol_guest], [guestaccess_withpassword,enrol_guest]
CPY [pluginname,enrol_guest], [guestaccess_withoutpassword,enrol_guest]
AMOS END
MDL-43135 Lang: removed redundant opentoguests
Merge branch 'wip-MDL-43135' of https://github.com/jennymgray/moodle
Merge branch 'wip-MDL-42174-master' of git://github.com/marinaglancy/moodle
Merge branch 'MDL-40517-master' of git://github.com/danpoltawski/moodle
Merge branch 'MDL-42959-master' of git://github.com/andrewnicols/moodle
Merge branch 'wip-MDL-43150-master' of git://github.com/marinaglancy/moodle
Merge branch 'w50_MDL-31625_m27_replace' of https://github.com/skodak/moodle
Merge branch 'wip-MDL-43279-master' of git://github.com/marinaglancy/moodle
Merge branch 'MDL-43252-master' of git://github.com/sammarshallou/moodle
Merge branch 'MDL-42796-master' of git://github.com/andrewnicols/moodle
Merge branch 'MDL-42815-master' of git://github.com/sammarshallou/moodle
Merge branch 'MDL-42625_master' of git://github.com/dmonllao/moodle
Merge branch 'MDL-43202-master' of git://github.com/andrewnicols/moodle
Merge branch 'MDL-38776-master' of git://github.com/andrewnicols/moodle
Merge branch 'MDL-38775-master' of git://github.com/andrewnicols/moodle
NOBUG: shifter rebuild
Merge branch 'MDL-42932_master' of https://github.com/markn86/moodle
Merge branch 'MDL-43071-master' of https://github.com/lucisgit/moodle
MDL-43218 navigation: Remove link to blogs when they are disabled