add KDGETLED subcommand to vtcol-bin

Actually we add both subcommand and sub-subcommand.

Example:

    [*] 15:52:40 phg@acheron vtcol $ vtcol leds get
    Caps: false, Num: true, Scroll: false

1 files changed, 27 insertions, 1 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 681177c..2ef43e8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -165,7 +165,7 @@ pub struct KbLedState(u8);
 
 impl KbLedState
 {
-    fn new(cap: bool, num: bool, scr: bool) -> Self
+    pub fn new(cap: bool, num: bool, scr: bool) -> Self
     {
         let mut state = 0u8;
 
@@ -175,6 +175,32 @@ impl KbLedState
 
         Self(state)
     }
+
+    #[inline]
+    pub fn get(con: &Console) -> io::Result<Self> { ioctl::kdgetled(con) }
+
+    #[inline]
+    pub fn cap(&self) -> bool { (self.0 & 0x4) != 0 }
+
+    #[inline]
+    pub fn num(&self) -> bool { (self.0 & 0x2) != 0 }
+
+    #[inline]
+    pub fn scr(&self) -> bool { (self.0 & 0x1) != 0 }
+}
+
+impl fmt::Display for KbLedState
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result
+    {
+        write!(
+            f,
+            "caps: {}, num: {}, scroll: {}",
+            self.cap(),
+            self.num(),
+            self.scr()
+        )
+    }
 }
 
 impl From<libc::c_char> for KbLedState