hgk: change config file from .gitk to .hgk

Git's gitk and Mercurial's hgk have diverged enough that their configuration information is no longer entirely compatible.  Whenever I run one, the other gets reset to the default screen position.  This patch changes hgk to store and read its configuration from ".hgk" instead of ".gitk", so as not to conflict with the "real" gitk anymore.

contrib/hgk

@@ -649,7 +649,7 b' proc savestuff {w} {'
     if {$stuffsaved} return
     if {![winfo viewable .]} return
     catch {
-	set f [open "~/.gitk-new" w]
+	set f [open "~/.hgk-new" w]
 	puts $f [list set mainfont $mainfont]
 	puts $f [list set curidfont $curidfont]
 	puts $f [list set textfont $textfont]
@@ -687,7 +687,7 b' proc savestuff {w} {'
 	puts $f "#"
 	puts $f "set authorcolors {$authorcolors}"
 	close $f
-	file rename -force "~/.gitk-new" "~/.gitk"
+	file rename -force "~/.hgk-new" "~/.hgk"
     }
     set stuffsaved 1
 }
@@ -3847,7 +3847,7 b' set authorcolors {'
     deeppink mediumorchid blue burlywood4 goldenrod slateblue red2 navy dimgrey
 }
 
-catch {source ~/.gitk}
+catch {source ~/.hgk}
 
 if {$curidfont == ""} {  # initialize late based on current mainfont
     set curidfont "$mainfont bold italic underline"