Dropped Z Axis raise line

[Isnogud77]

First of all many thanks for this tool. I was super happy to find this.

I optimized one of my sample g-code files that really performs a lot of nonsense seek operations. What I noticed from the output of the tool is that it dropped one line of the input. It looks like it is the first G0 Z15 command which is there to raise the spindle to it's safety height.

Apart from that the optimized program worked properly and reduced the time from ~21min to ~17min!

Another output of the program was:
WARNING!!!! Program Ends with cutter down, Z = -2.00

But actually the last command in the optimized program is G0 Z15, so this warning is clearly wrong.