Account for spacing in MapFont#getWidth()

Previously, this method did not account for the 1-px space inserted
after each character, leading to an inaccurate result.
Allow newlines and colors in MapFont#getWidth()

MapFont#getWidth() validates text before it calculates length: the text
must consist of the supported printable characters, newlines, or color
codes (\u00A7).

This change to MapFont#getWidth() fixes inaccurate width calculations
for input text with newlines or color codes.