as a starting point
* Make double Distance() take double arguments and remove internal range checking.
* Start on EDA_DRAW_FRAME::AdjustScrollBars() and use "double" for most all calculations
in anticipation of setting INT_MAX INT_MIN limits eventually.
Eeschema: cleaning code. Start work to enhance annotation algorithm.
Already added an option to annotate using sheet number (sheet 1 uses numbers 100 to 199, sheet 2 uses 200 to 299..).
Works fine if deleting existing annotation, but needs work to be used when the existing annotation is kept .