Ensure an absolute path is added to sys.path

Closes gh-221

doc/cfgfile.rst

@@ -43,7 +43,7 @@ Application section
        import sys, os
        import site
 
-       scriptdir, script = os.path.split(__file__)
+       scriptdir, script = os.path.split(os.path.abspath(__file__))
        pkgdir = os.path.join(scriptdir, 'pkgs')
        # Ensure .pth files in pkgdir are handled properly
        site.addsitedir(pkgdir)

nsist/__init__.py

@@ -234,7 +234,7 @@ class InstallerBuilder(object):
     SCRIPT_TEMPLATE = """#!python{qualifier}
 import sys, os
 import site
-scriptdir, script = os.path.split(__file__)
+scriptdir, script = os.path.split(os.path.abspath(__file__))
 installdir = scriptdir  # for compatibility with commands
 pkgdir = os.path.join(scriptdir, 'pkgs')
 sys.path.insert(0, pkgdir)