Support Arch Linux as host

Script names and setup steps are slightly modified. Container creation step is now separated, so users can create the container according to their distro specific procedures.

Fixed workarounds

Build process is stripped down to these 3 commands:

git clone https://github.com/ceremcem/build-freecad-asm3
cd build-freecad-asm3/tools
./auto.sh [--freecad-src /path/to/FreeCAD]

Native-like performance

By using run-in-chroot.sh script, FreeCAD now can be run in native speeds:

./run-in-chroot.sh -n fc -u freecad 'fc-build/Release/bin/FreeCAD'

Use Qt5 and Python3

This release makes it possible to compile FreeCAD against Qt5 and Python3. Instructions to create LXC is now easier and more straightforward.

v1.0

Update README.md