Allow end-positioning a drop-down menu

[maccabeelevine]

If the content of a menu item is wide, it can force the menu off the screen (creating a horizontal scroll bar):

This allows setting bootstrap classes on the dropdown-menu such as dropdown-menu-end, to right-align the menu.

In HeaderBar-allLangs.phtml:

'menuClass' => 'dropdown-menu-end',

[maccabeelevine]

FWIW in bootstrap3, the menus were end-aligned by default. Not sure if the change was intentional, I think largely it was a good change. But for menus on the right edge of the screen (we have an extra menu) it's a problem.

[EreMaijala]

While I'm fine with adding the menuClass parameter it would be framework-specific, which is a thing to avoid when possible. So I think that alignment should be a top-level parameter to keep it framework-agnostic, or in other words to keep the implementation more opaque. Internally it would set the relevant bootstrap classes.

[EreMaijala]

Maybe use htmlAttributes helper for all attributes so that we can avoid any extra whitespace etc.

[maccabeelevine]

@EreMaijala I made both changes. Usage now

'menuAlign' => 'end',

[demiankatz]

Looks reasonable to me, but I'll wait for @EreMaijala's final confirmation before merging. :-)

[EreMaijala]

Looks good to me too. :)