Fix unreacheable condition block
Fix unreacheable condition block

Reported by GCC:
src/HDxf.cpp:391:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]

In best case, no layers names were discarded when importing DXF.

This commit changes wxString::find() to wxString::Find() and test it against wxNOT_FOUND to know if string was found.
Some doc improvement included...
AlanZheng/heekscad,namoamitof/heekscad,thojongle/heekscad,ahmetsemihparlak/heekscad,tectronics/heekscad,AlanZheng/heekscad,Nurb432/heekscad,ahmetsemihparlak/heekscad,tectronics/heekscad,DINKIN/heekscad,Nurb432/heekscad,ahmetsemihparlak/heekscad,pyrotron/heekscad,singwina/heekscad,DINKIN/heekscad,tectronics/heekscad,pyrotron/heekscad,thojongle/heekscad,thojongle/heekscad,FluffyMortain/heekscad,FluffyMortain/heekscad,namoamitof/heekscad,tbinias/heekscad,pyrotron/heekscad,DINKIN/heekscad,singwina/heekscad,Powerino73/heekscad,AlanZheng/heekscad,pyrotron/heekscad,tbinias/heekscad,singwina/heekscad,AlanZheng/heekscad,FluffyMortain/heekscad,DINKIN/heekscad,ahmetsemihparlak/heekscad,Nurb432/heekscad,tbinias/heekscad,Powerino73/heekscad,Nurb432/heekscad,namoamitof/heekscad,Powerino73/heekscad,namoamitof/heekscad,singwina/heekscad,thojongle/heekscad,tbinias/heekscad,Powerino73/heekscad,FluffyMortain/heekscad,tectronics/heekscad