input: allow - as separator between commands, instead of _

Wnile it seems quite logical to me that commands use _ as word
separator, while properties use -, I can't really explain the
difference, and it tends to confuse users as well. So always
prefer - as separator for everything.

Using _ still works, and will probably forever. Not doing so would
probably create too much chaos and confusion.

etc/input.conf

@@ -12,7 +12,7 @@
 # Use 'ignore' to unbind a key fully (e.g. 'ctrl+a ignore').
 #
 # Strings need to be quoted and escaped:
-#   KEY show_text "This is a single backslash: \\ and a quote: \" !"
+#   KEY show-text "This is a single backslash: \\ and a quote: \" !"
 #
 # You can use modifier-key combinations like Shift+Left or Ctrl+Alt+x with
 # the modifiers Shift, Ctrl, Alt and Meta (may not work on the terminal).
@@ -56,8 +56,8 @@
 #Shift+UP    no-osd seek  5 exact
 #Shift+DOWN  no-osd seek -5 exact
 # Skip to previous/next subtitle (subject to some restrictions; see manpage)
-#Ctrl+LEFT   no-osd sub_seek -1
-#Ctrl+RIGHT  no-osd sub_seek  1
+#Ctrl+LEFT   no-osd sub-seek -1
+#Ctrl+RIGHT  no-osd sub-seek  1
 #PGUP add chapter 1                     # skip to next chapter
 #PGDWN add chapter -1                   # skip to previous chapter
 #Shift+PGUP seek 600
@@ -68,21 +68,21 @@
 #} multiply speed 2.0
 #BS set speed 1.0                       # reset speed to normal
 #q quit
-#Q quit_watch_later
+#Q quit-watch-later
 #q {encode} quit
 #ESC set fullscreen no
 #ESC {encode} quit
 #p cycle pause                          # toggle pause/playback mode
-#. frame_step                           # advance one frame and pause
-#, frame_back_step                      # go back by one frame and pause
+#. frame-step                           # advance one frame and pause
+#, frame-back-step                      # go back by one frame and pause
 #SPACE cycle pause
-#> playlist_next                        # skip to next file
-#ENTER playlist_next                    # skip to next file
-#< playlist_prev                        # skip to previous file
+#> playlist-next                        # skip to next file
+#ENTER playlist-next                    # skip to next file
+#< playlist-prev                        # skip to previous file
 #O osd                                  # cycle through OSD mode
-#o show_progress
-#P show_progress
-#I show_text "${filename}"              # display filename in osd
+#o show-progress
+#P show-progress
+#I show-text "${filename}"              # display filename in osd
 #z add sub-delay -0.1                   # subtract 100 ms delay from subs
 #x add sub-delay +0.1                   # add
 #ctrl++ add audio-delay 0.100           # this changes audio/video sync
@@ -110,7 +110,7 @@
 #V cycle ass-vsfilter-aspect-compat
 # switch between applying no style overrides to SSA/ASS subtitles, and
 # overriding them almost completely with the normal subtitle style
-#u cycle_values ass-style-override "force" "no"
+#u cycle-values ass-style-override "force" "no"
 #j cycle sub                            # cycle through subtitles
 #J cycle sub down                       # ...backwards
 #SHARP cycle audio                      # switch audio streams
@@ -124,7 +124,7 @@
 #w add panscan -0.1                     # zoom out with -panscan 0 -fs
 #e add panscan +0.1                     #      in
 # cycle video aspect ratios; "-1" is the container aspect
-#A cycle_values video-aspect "16:9" "4:3" "2.35:1" "-1"
+#A cycle-values video-aspect "16:9" "4:3" "2.35:1" "-1"
 #POWER quit
 #PLAY cycle pause
 #PAUSE cycle pause
@@ -132,8 +132,8 @@
 #STOP quit
 #FORWARD seek 60
 #REWIND seek -60
-#NEXT playlist_next
-#PREV playlist_prev
+#NEXT playlist-next
+#PREV playlist-prev
 #VOLUME_UP add volume 2
 #VOLUME_DOWN add volume -2
 #MUTE cycle mute
@@ -141,7 +141,7 @@
 #CLOSE_WIN {encode} quit
 #E cycle edition                        # next edition
 #l ab_loop                              # Set/clear A-B loop points
-#L cycle_values loop "inf" "no"         # toggle infinite looping
+#L cycle-values loop "inf" "no"         # toggle infinite looping
 #ctrl+c quit
 
 # Apple Remote section
@@ -153,7 +153,7 @@
 #AR_NEXT_HOLD seek 120
 #AR_PREV seek -10
 #AR_PREV_HOLD seek -120
-#AR_MENU show_progress
+#AR_MENU show-progress
 #AR_MENU_HOLD cycle mute
 #AR_VUP add volume 2
 #AR_VUP_HOLD add chapter 1
@@ -191,9 +191,9 @@
 
 # ? add sub-scale +0.1                  # increase subtitle font size
 # ? add sub-scale -0.1                  # decrease subtitle font size
-# ? sub_step -1                         # immediately display next subtitle
-# ? sub_step +1                         #                     previous
-# ? cycle_values window-scale 0.5 2 1   # switch between 1/2, 2x, unresized window size
+# ? sub-step -1                         # immediately display next subtitle
+# ? sub-step +1                         #                     previous
+# ? cycle-values window-scale 0.5 2 1   # switch between 1/2, 2x, unresized window size
 # ? cycle colormatrix
 # ? add audio-delay 0.100               # this changes audio/video sync
 # ? add audio-delay -0.100