Fixes to 'define sliders' and 'select the functions to import'

'define sliders':
- Don't strip some info for 'clip' and 'var' arguments
- Don't show horizontal scrollbar

'select the functions to import':
- Always show the dialog when importing from wiki
- Sort filter list case-insensitively
Improve 'filter help file' option

Search also for the plugin name, e.g. f3kdb -> f3kdb.txt, flash3kyuu.txt etc.
Improve 'select the functions to import' contextual menu
Add 'autocomplete parameter' menu option, Ctrl+Alt+Space shortcut
Fix c9586997 and 41dd8e8b on wxPython 2.8