REQ: cfg_SAVE all unbinded keys (except escape, not usable)

[Matrix-QW]

Is your feature request related to a problem? Please describe.
It's not possible to bind some keys using the console with my keyboard layout (spanish), only through the menu.
Also, there are additional keys that can be used but the menu doesn't differentiate keypad keys and left/right for shift/alt/ctrl/winkey preceded by an L/R to be used with sys_disableWinKeys 1, and you have to know their names, like:

• PRINTSCR ; SCRLCK ; PAUSE ; POPUPMENU ; LWINKEY ; RWINKEY

Another problem is that cfg_save doesn't keep L/R for special keys like LALT/RALT and are saved as ALT.
Also avoid adding a new line at the end of the config.
cfg_backup 1 should be made default in case an unintended cfg_save is done.

Describe the solution you'd like
Save all bindable keys in the current keyboard layout including L/R special keys.

Additional context
Some binds could be made default to make it more intuitive and easier to manage ezQ.

bind PRINTSCR "screenshot" // this is what I use
bind f12 "quit"
bind f11 "windows" // very useful with sys_disableWinKeys 1 and if there are no open tasks it will still go to desktop, not like alt+tab.
bind F1 "toggleready"
bind F2 "agree"
bind F3 "togglespec"
bind F4 "connect $lastip"

Note: hud_export saves the file as utf-8 which screws some chars, it should save it as ANSI.