Remove apostrophes from instances of possessive "its".

I noticed one instance of this while looking at the code the other day,
and after a quick grep, realized it happened a *lot*!  One of the many
frustrating things about the English language is that we use apostrophes
to make pretty much everything possessive *except* the pronoun "it".
In that case, we use "its".  "It's" is reserved for the contraction
meaning "it is" or "it has".

NEWS

@@ -1643,7 +1643,7 @@ raising/lowering there is a time threshold before raising/lowering.
 The thresholds can be changed in wconfig.h by changing one or both of
 AUTO_LOWER_DELAY and AUTO_RAISE_DELAY (expressed in milliseconds).
 For example if you set AUTO_RAISE_DELAY to 0, then the Clip will be raised as
-soon as the mouse pointer enters it's area. Setting AUTO_RAISE_DELAY to a very
+soon as the mouse pointer enters its area. Setting AUTO_RAISE_DELAY to a very
 big value, will make the Clip to practically do not auto raise unless clicked,
 but to be automatically lowered after AUTO_LOWER_DELAY (ms) when leaved.
 
@@ -2572,7 +2572,7 @@ The OPEN_MENU command now supports the following syntax:
    // it in current position
    OPEN_MENU file.menu
 2. Pipe menu handling.
-   // opens command and uses it's stdout to construct menu.
+   // opens command and uses its stdout to construct menu.
    // Command's output must be a valid menu description.
    OPEN_MENU | command
 3. Directory handling.
@@ -3175,7 +3175,7 @@ when they are first mapped
 titlebar gradients are in a single piece now
 
 the WMDock file was merged into the WMState file. You can insert this
-file in WMState and set it's key to Dock. For example, if your WMDock
+file in WMState and set its key to Dock. For example, if your WMDock
 contains:
 
 {