Added a few new functions to my branch

[LennartHennigs]

Hey,
I am currently using your library in a project of mine and really appreciate the huge amount of work and thought that went into it. So, first of all: thank you.

In my fork I added a few functions to the library:

bool ezMenu::updateItemName(int16_t index, String str)
void ezMenu::setSelected(int16_t index, bool refresh /* = false */) 
int16_t ezMenu::getSelected()
String ezMenu::getItemName(int16_t index)
bool ezMenu::updateItemState(int16_t index, String str)

...and I updated _runTextOnce(), it will now skip empty entries when navigating in a menu – the empty line allows me to separate a function from entries.

The use case for the functions is that I use submenus to select certain parameters (shown as states). These parameters are shown in the main menu. And the parameter show in the main menu should be selected in the sub menu

Maybe you'll it useful and consider merging it back.

Cheers
l.