Allowing to explicity specify a format

Most tools and functions now allow to explicitly
specify a format for input and output. On input,
the format is usually detected, but for some
cases, this is not possible (e.g. DEF). So you can
specify the format attached to the file name in
square brackets:

e.g. file.defok[def]

"def" is the intended suffix, "defok" is the given one.

On output, the same is possible, specifically in strmxor
and strmclip:

strmxor a.gds b.gds out.xor[oas]

testdata/lefdef/issue-489/in.d

@@ -0,0 +1,34 @@
+VERSION 5.7 ;
+DIVIDERCHAR "/" ;
+BUSBITCHARS "[]" ;
+DESIGN test ;
+UNITS DISTANCE MICRONS 2000 ;
+
+DIEAREA ( 0 0 ) ( 37520 7840 ) ;
+
+PINS 12 ;
+- VDD + NET VDD + SPECIAL + DIRECTION INOUT + USE POWER
+  + LAYER M2 ( -320 0 ) ( 320 37520 )
++ FIXED ( 37520 3920 ) W ;
+- VSS + NET VSS + SPECIAL + DIRECTION INOUT + USE GROUND
+ + PORT
+  + LAYER M2 ( -18760 0 ) ( 18760 640 )
++ FIXED ( 18760 -320 ) N
+ + PORT
+  + LAYER M2 ( -18760 0 ) ( 18760 640 )
++ FIXED ( 18760 8160 ) S
+ ;
+END PINS
+
+SPECIALNETS 4 ;
+- VSS  ( * VSS )
++ ROUTED M2 640 + SHAPE FOLLOWPIN ( 0 0 ) ( 37520 * )
+NEW M2 640 + SHAPE FOLLOWPIN ( 0 7840 ) ( 37520 * )
+  + USE GROUND
+ ;
+- VDD  ( * VDD )
++ ROUTED M2 640 + SHAPE FOLLOWPIN ( 0 3920 ) ( 37520 * )
+  + USE POWER
+ ;
+END SPECIALNETS
+END DESIGN

testdata/lefdef/issue-489/in.l

@@ -0,0 +1,63 @@
+VERSION 5.7 ;
+
+BUSBITCHARS "[]" ;
+DIVIDERCHAR "/" ;
+UNITS
+	DATABASE MICRONS 1000 ;
+END UNITS
+
+MANUFACTURINGGRID 0.002 ;
+
+USEMINSPACING OBS OFF ;
+
+LAYER overlap
+	TYPE OVERLAP ;
+END overlap
+
+LAYER contact
+	TYPE CUT ;
+END contact
+
+LAYER metal1
+	TYPE ROUTING ;
+	DIRECTION HORIZONTAL ;
+END metal1
+
+LAYER via1
+	TYPE CUT ;
+END via1
+
+LAYER metal2
+	TYPE ROUTING ;
+	DIRECTION VERTICAL ;
+END metal2
+
+LAYER via2
+	TYPE CUT ;
+END via2
+
+LAYER metal3
+	TYPE ROUTING ;
+	DIRECTION HORIZONTAL ;
+END metal3
+
+LAYER via3
+	TYPE CUT ;
+END via3
+
+LAYER metal4
+	TYPE ROUTING ;
+	DIRECTION VERTICAL ;
+END metal4
+
+LAYER via4
+	TYPE CUT ;
+END via4
+
+LAYER metal5
+	TYPE ROUTING ;
+	DIRECTION HORIZONTAL ;
+END metal5
+
+
+END LIBRARY

testdata/lefdef/strm2oas_small/in.defok

@@ -0,0 +1,29 @@
+
+VERSION 5.6 ;
+NAMESCASESENSITIVE ON ;
+DIVIDERCHAR "/" ;
+BUSBITCHARS "<>" ;
+DESIGN SMALL ;
+UNITS DISTANCE MICRONS 100 ;
+
+DIEAREA ( -30 -30 ) ( 1030 1030 ) ;
+
+VIAS 1 ;
+- via1_960x340
++ VIARULE Via1Array-0
+  + CUTSIZE 140 140
+  + LAYERS metal1 via1 metal2 
+  + CUTSPACING 160 160
+  + ENCLOSURE 110 100 110 100
+  + ROWCOL 1 3
+;
+END VIAS
+
+SPECIALNETS 1 ;
+- VDD ( * VDD )
++ ROUTED metal1 0 + SHAPE STRIPE ( 500 500 ) via1_960x340
++ USE POWER ;
+END SPECIALNETS
+
+END DESIGN
+