Implemented native gzip compression/decompression using zlib routines.

Compression levels of the output can be controlled with the "gds
compress [<value>]" command, where <value> 0 (default) is uncompressed
output, 6 is "normal" gzip compression, and 9 is maximum compression.

calma/CalmaWrite.c

@@ -66,6 +66,10 @@ bool CalmaAllowUndefined = FALSE; /* If TRUE, allow calls to undefined cells */
 bool CalmaContactArrays = FALSE; /* If TRUE, output contacts as subcell arrays */
 bool CalmaMergeTiles = FALSE;	 /* If TRUE, merge tiles into polygons in output. */
 
+#ifdef HAVE_ZLIB
+int  CalmaCompression = 0;	/* Output file compression level (0 = uncompressed) */
+#endif
+
     /* Forward declarations */
 extern int calmaWriteInitFunc();
 extern int calmaWriteMarkFunc();
@@ -286,7 +290,7 @@ CalmaWrite(rootDef, f)
     CellDef *rootDef;	/* Pointer to CellDef to be written */
     FILE *f;		/* Open output file */
 {
-    int oldCount = DBWFeedbackCount, problems;
+    int oldCount = DBWFeedbackCount, problems, nerr;
     bool good;
     CellUse dummy;
     HashEntry *he;