style: declare globals properly

By default, `typeset` defines variables locally unless in the main scope.
This is specially bad when using `omz plugin load`, which happens inside
a function, so the declared variables don't continue being defined when
the function finishes and the main scope reappears.

themes/dieter.zsh-theme

@@ -6,7 +6,7 @@
 # The exit code visual cues will only display once.
 # (i.e. they will be reset, even if you hit enter a few times on empty command prompts)
 
-typeset -A host_repr
+typeset -g -A host_repr
 
 # translate hostnames into shortened, colorcoded strings
 host_repr=('dieter-ws-a7n8x-arch' "%{$fg_bold[green]%}ws" 'dieter-p4sci-arch' "%{$fg_bold[blue]%}p4")

themes/jonathan.zsh-theme

@@ -66,7 +66,7 @@ if [[ "${langinfo[CODESET]}" = UTF-8 ]]; then
   PR_LRCORNER="┘"
   PR_URCORNER="┐"
 else
-  typeset -A altchar
+  typeset -g -A altchar
   set -A altchar ${(s..)terminfo[acsc]}
   # Some stuff to help us draw nice lines
   PR_SET_CHARSET="%{$terminfo[enacs]%}"