Fixed scaling bug in dialog textbox.

See: http://tinyurl.com/bfcx4po

Changes:

a) Text and images are correctly scaled now.

b) Size and positioning of text and images in textbox can now be set via             percentage values in helper.js

c) Removed lineletters attribute from dialogSettings(). Instead the maximum number of chars per line is now calculated by a rough formula

((textboxWidth - textStartPos) / pixelSize) + someOffset

Currently someOffset is the lineDistance, which might be changed in future versions!