Prompt to overwrite in Windows Save As dialog

Add OFN_OVERWRITEPROMPT so the dialog will prompt before overwriting an existing file.
Remove the OFN_FILEMUSTEXIST flag, which works only with Open dialogs.
TM: simplify match test for current tag
TM: don't needlessly duplicate array when searching for current tag
Use rst2pdf instead of rst2latex and pdflatex to generate PDF manual
Merge branch 'b4n/use-rst2pdf'
Fix Waf build for recent Doxyfile changes

Recent changes to Doxyfile.in added new placeholders the build system
has to replace, and Waf recognized them but failed, not knowing what to
replace them with.
Fix UI updating after loading a project

When loading a project and focusing the last document, the UI wouldn't
get properly updated for the displayed file -- because for performance
reasons we disable notebook page switch handlers when loading session
files.  Fix this by synthesizing a notebook page switch event when done
loading.
Update of Japanese translation
CSS: fix mappings to non-existing styles
CSS: remove some pseudo elements listed as pseudo classes
Disable commenting out blank lines by 'Toggle line commentation'
Add VBS extension to FreeBasic syntax

Just adding '*.vbs' to 'FreeBasic' line.
Replace tabs with 4 spaces in main.py template
Simulate `main` function in Python
Update Vala file template

Vala is not Java
Adding an HTML5-template in addition to xhtml 1.0 strict one
Add more details about menu mnemonics
Reword "replace by tabs/spaces" as "replace with"
Fix some conflicting mnemonics in the menus
Keep exact menu item string as keybinding label

Using the exact same string avoids duplicate translation, and here only
mnemonic changes were introduced with commit
95306ac8db4fc38ad7ba7e172328cef5117efaf0.