add python setuptools support

- add setup.py script,
 - switch to use images via "share:" resource name
   (this allows to work both versions of application:
     - system wide installation,
     - directly from source),
 - add .desktop file,
 - rename FlatCAM.py to flatcam and install it as an
   executable script.

setup.py

@@ -0,0 +1,75 @@
+############################################################
+# FlatCAM: 2D Post-processing for Manufacturing            #
+# http://flatcam.org                                       #
+# Author: Damian Wrobel <dwrobel@ertelnet.rybnik.pl>       #
+# Date: 05/23/2017                                         #
+# MIT Licence                                              #
+# A setuptools based setup module                          #
+############################################################
+
+from setuptools import setup
+import glob
+
+setup(
+    name='FlatCAM',
+
+    version='8.5',
+
+    description='2D Computer-Aided PCB Manufacturing',
+
+    long_description=('FlatCAM is a program for preparing CNC jobs for making'
+                      'PCBs on a CNC router. Among other things, it can take'
+                      'a Gerber file generated by your favorite PCB CAD'
+                      'program, and create G-Code for Isolation routing.'),
+
+    url='http://flatcam.org/',
+
+    author='Juan Pablo Caram',
+
+    license='MIT',
+
+    packages=[
+        'descartes',
+        'tclCommands'
+    ],
+
+    py_modules=[
+        "camlib",
+        "DblSidedTool",
+        "FlatCAMApp",
+        "FlatCAMCommon",
+        "FlatCAMDraw",
+        "FlatCAMGUI",
+        "FlatCAMObj",
+        "FlatCAMProcess",
+        "FlatCAMShell",
+        "FlatCAMTool",
+        "FlatCAMVersion",
+        "FlatCAMWorker",
+        "GUIElements",
+        "MeasurementTool",
+        "ObjectCollection",
+        "ObjectUI",
+        "PlotCanvas",
+        "svgparse",
+        "termwidget"
+    ],
+
+    install_requires=[
+        'simplejson',
+        'numpy>=1.8',
+        'scipy',
+        'matplotlib>=1.3.1',
+        'shapely>=1.3'
+        'rtree',
+        'svg.path'
+    ],
+
+    include_package_data=True,
+
+    data_files=[
+        ('share/flatcam', glob.glob('share/*'))
+    ],
+
+    scripts=['flatcam']
+)