gateone.js:  Modified GateOne.Utils.getEmDimensions() to use the letter "M" instead of a full-size unicode block character because apparently that character is missing from a lot of fonts.  Using "M" doesn't seem to have any impact on the accuracy of the function in testing so it shouldn't pose any problems (despite the fact that in theory the M character may not be as tall as a full block).  Shouldn't run into this problem again unless the font in question is missing the letter "M".