[tlbuild] asymptote search path

[John Bowman]

Hi all,

Uninstalling one version of asy (perhaps before installing another version)
should certainly not remove the history files ~/.asy/history*
(which contains data typed by the user).

In svn (will be in the 1.83 release, which is planned for tonight), I have
changed item 3 in the Asymptote search path:

1. The current directory;

2. A list of one or more directories specified by the configuration
variable dir (separated by : under UNIX and ; under MSDOS);

3. The directory specified by the environment variable ASYMPTOTE_HOME; if
this variable is not set, the directory .asy in the user's home directory
(%USERPROFILE%\.asy under MSDOS) is used;

4. The Asymptote system directory (by default, /usr/local/share/asymptote under
UNIX and C:\Program Files\Asymptote under MSDOS).

Index: settings.cc
===================================================================
--- settings.cc (revision 4581)
+++ settings.cc (working copy)
@@ -1325,13 +1325,16 @@
       string texmf=s+dirsep+"texmf"+dirsep;
       docdir=texmf+"doc"+dirsep+"asymptote";
       Setting("sysdir")=texmf+"asymptote";
-      s=lookup("TEXMFCONFIG");
+      s=lookup("ASYMPTOTE_HOME");
       if(s.size() > 1)
-        initdir=s+dirsep+"asymptote";
+        initdir=s;
     }
   } 
   
   if(initdir.empty())
+    initdir=Getenv("ASYMPTOTE_HOME",msdos);
+  
+  if(initdir.empty())
     initdir=Getenv(HOME.c_str(),msdos)+dirsep+"."+suffix;
   
 #ifdef __CYGWIN__