installer: fix 2 Python related bugs

see the changelog for the fixed bugs

development/Win32/packaging/installer/ChangeLog.txt

@@ -1,12 +1,21 @@
-Changelog for LyX-213-2:
+Changelog for LyX-214-2:
+- fix bug that viewing/exporting of some file formats failed because of
+  unknown executable for .py files
+- updated to Python 2.7.10 (fixes problems that LyX got erroneous if
+  Python 2.7.10 was installed before LyX)
+
+
+Changelog for LyX-214-1:
+- installs LyX 2.1.4
 - fixes problems with viewing PDF files
   NOTE: If you use Adobe Reader as PDF viewer the view is updated by pressing
         again the view button in LyX while the update button does nothing
 - new method to view/export LyX files to OpenDocument and MS Word
 - updated Slovak translation of the installer
 - updated to Ghostscript 9.16
-- updated spell-checker dictionaries for English (GB), English (US), Portuguese,
+- updated to Qt 4.8.7
-  Spanish, Spanish (MX) and Turkish
+- updated spell-checker dictionaries for Catalan, English (GB), English (US),
+  Portuguese, Scottish Gaelic, Spanish, Spanish (MX) and Turkish
   (To benefit from them you must uninstall an already installed LyX 2.1.x and
    then use this installer.)
 - updated thesaurus for English (US), Portuguese and Spanish

development/Win32/packaging/installer/setup/install.nsh

@@ -77,6 +77,14 @@ Section -ProgramFiles SecProgramFiles
   SetOutPath "$INSTDIR"
   # recursively copy all files under Python
   File /r "${FILES_PYTHON}"
+  # register .py files if necessary
+  ReadRegStr $0 SHCTX "Software\Classes\Python.File\shell\open\command" ""
+  ${if} $0 == "" # if nothing was found
+   WriteRegStr SHCTX "Software\Classes\Python.File\shell\open\command" "" '"$INSTDIR\Python\python.exe" "%1" %*'
+   WriteRegStr SHCTX "Software\Classes\Python.File\DefaultIcon" "" "$INSTDIR\Python\DLLs\py.ico"
+   WriteRegStr SHCTX "Software\Classes\.py" "" "Python.File"
+   WriteRegStr SHCTX "Software\Classes\Python.File" "OnlyWithLyX" "Yes${APP_SERIES_KEY}" # special entry to test if they were registered by this LyX version
+  ${endif}
   
   # Compile all Pyton files to byte-code
   # The user using the scripts may not have write access

development/Win32/packaging/installer/setup/uninstall.nsh

@@ -25,6 +25,10 @@ Section "un.LyX" un.SecUnProgramFiles
   
   # Python
   RMDir /r "$INSTDIR\python"
+  ReadRegStr $0 SHCTX "Software\Classes\Python.File" "OnlyWithLyX" # test if it was registered by this LyX version
+  ${if} $0 == "Yes${APP_SERIES_KEY}"
+   DeleteRegKey SHCTX "Software\Classes\Python.File"
+  ${endif}
   
   # ImageMagick
   RMDir /r "$INSTDIR\imagemagick"