Visual Studio: Make gen-gdkversionmacros-h.py generic

Rename the script as gen-version-items.py, and so make things more generic and
usable by other items in the build.  We want to eventually to be able to
generate the .rc files and the *version*.h files from their *.in counterparts
using this script.

win32/gen-version-items.py

@@ -0,0 +1,46 @@
+#!/usr/bin/python3
+
+# Generate various items with version info
+
+# Author: Fan, Chun-wei
+# Date: July 25, 2019
+
+import os
+import sys
+import argparse
+
+from replace import replace_multi, replace
+
+def main(argv):
+    srcdir = os.path.dirname(__file__)
+    top_srcdir = os.path.join(srcdir, os.pardir)
+    parser = argparse.ArgumentParser(description='Generate various items with version info')
+    parser.add_argument('--version', help='Version of the package',
+                        required=True)
+    parser.add_argument('--interface-age', help='Interface age of the package',
+                        required=True)
+    parser.add_argument('--source', help='Source file template to process',
+                        required=True)
+    parser.add_argument('--output', '-o', help='Output generated file location',
+                        required=True)
+    args = parser.parse_args()
+    gdk_sourcedir = os.path.join(top_srcdir, 'gdk')
+    version_parts = args.version.split('.')
+    # (100 * gtk_minor_version + gtk_micro_version - gtk_interface_age)
+    binary_age = (int(version_parts[1]) * 100) + int(version_parts[2])
+    lt_current = (int(version_parts[1]) * 100) + int(version_parts[2]) - int(args.interface_age)
+    lt_age = binary_age - int(args.interface_age)
+
+    version_info_replace_items = {'@GTK_MAJOR_VERSION@':    version_parts[0],
+                                  '@GTK_MINOR_VERSION@':    version_parts[1],
+                                  '@GTK_MICRO_VERSION@':    version_parts[2],
+                                  '@GTK_API_VERSION@':      '3.0',
+                                  '@GTK_VERSION@':          args.version,
+                                  '@GTK_BINARY_AGE@':       str(binary_age),
+                                  '@GTK_INTERFACE_AGE@':    args.interface_age,
+                                  '@LT_CURRENT_MINUS_AGE@': str(lt_current - lt_age)}
+
+    replace_multi(args.source, args.output, version_info_replace_items)
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv))