Add additional video player keyboard shortcuts (#275)

*  Skip forward 10 seconds ((CMD OR CTRL) ALT right)
 Skip back 10 seconds ((CMD OR CTRL) ALT left)
 Increase video speed ((CMD OR CTRL) +)
 Decrease video speed ((CMD OR CTRL) -)

* Codestyle fix

* The 'steps' should be implemented in base2, standard players use 1x, 2x, 4x, 8x, 16x

fixed bug with shift + "=" which is "+"

* resolve conflicts

* remove ide specific data
make playback rate more granular
add to menu skip and speed entries

* intendation fix

* conflict resolve

* rename setPlaybackRate to changePlaybackRate
setRate return boolean depending on whether this cast target supports setting the playback rate.
if setRate returns false - don`t change state
redundant else if statement in changePlaybackRate function

main/menu.js

@@ -92,6 +92,30 @@ function openSubtitles () {
   }
 }
 
+function skipForward () {
+  if (windows.main) {
+    windows.main.send('dispatch', 'skip', 1)
+  }
+}
+
+function skipBack () {
+  if (windows.main) {
+    windows.main.send('dispatch', 'skip', -1)
+  }
+}
+
+function increasePlaybackRate () {
+  if (windows.main) {
+    windows.main.send('dispatch', 'changePlaybackRate', 1)
+  }
+}
+
+function decreasePlaybackRate () {
+  if (windows.main) {
+    windows.main.send('dispatch', 'changePlaybackRate', -1)
+  }
+}
+
 function onWindowShow () {
   log('onWindowShow')
   getMenuItem('Full Screen').enabled = true
@@ -110,6 +134,10 @@ function onPlayerOpen () {
   getMenuItem('Increase Volume').enabled = true
   getMenuItem('Decrease Volume').enabled = true
   getMenuItem('Add Subtitles File...').enabled = true
+  getMenuItem('Skip forward 10 seconds').enabled = true
+  getMenuItem('Skip back 10 seconds').enabled = true
+  getMenuItem('Increase video speed').enabled = true
+  getMenuItem('Decrease video speed').enabled = true
 }
 
 function onPlayerClose () {
@@ -118,6 +146,10 @@ function onPlayerClose () {
   getMenuItem('Increase Volume').enabled = false
   getMenuItem('Decrease Volume').enabled = false
   getMenuItem('Add Subtitles File...').enabled = false
+  getMenuItem('Skip forward 10 seconds').enabled = false
+  getMenuItem('Skip back 10 seconds').enabled = false
+  getMenuItem('Increase video speed').enabled = false
+  getMenuItem('Decrease video speed').enabled = false
 }
 
 function onToggleFullScreen (isFullScreen) {
@@ -311,6 +343,36 @@ function getAppMenuTemplate () {
           label: 'Add Subtitles File...',
           click: openSubtitles,
           enabled: false
+        },
+        {
+          type: 'separator'
+        },
+        {
+          label: 'Skip forward 10 seconds',
+          accelerator: 'CmdOrCtrl+Alt+Right',
+          click: skipForward,
+          enabled: false
+        },
+        {
+          label: 'Skip back 10 seconds',
+          accelerator: 'CmdOrCtrl+Alt+Left',
+          click: skipBack,
+          enabled: false
+        },
+        {
+          type: 'separator'
+        },
+        {
+          label: 'Increase video speed',
+          accelerator: 'CmdOrCtrl+plus',
+          click: increasePlaybackRate,
+          enabled: false
+        },
+        {
+          label: 'Decrease video speed',
+          accelerator: 'CmdOrCtrl+-',
+          click: decreasePlaybackRate,
+          enabled: false
         }
       ]
     },