improve DXF file handling functions:

- DM_LINE mode support to generate Excellon routing sequence
- DM_MOUSE_BITES mode support to generate mouse bites along all path also,  not only line object

tests/expects/dxf_offset.gtl

@@ -25,11 +25,6 @@ X210000Y60000D01*
 G02*
 X200000Y50000I-10000J0D01*
 G01*
-X119171Y100000D02*
-G75*
-G03*
-X119171Y100000I-3000J0D01*
-G01*
 X119171Y125107D02*
 G75*
 G02*
@@ -38,4 +33,9 @@ G01*
 X116171Y125107D01*
 G01*
 X119171Y125107D01*
+G01*
+X119171Y100000D02*
+G75*
+G02*
+X119171Y100000I-3000J0D01*
 M02*

tests/expects/dxf_rectangle_inch.gtl

@@ -6,15 +6,14 @@ G75*
 %LPD*%
 D10*
 G01*
-X0Y0D02*
+X0Y39370D02*
+G75*
+G01*
+X0Y0D01*
+G01*
 X39370Y0D01*
 G01*
-X39370Y0D02*
 X39370Y39370D01*
 G01*
-X39370Y39370D02*
 X0Y39370D01*
-G01*
-X0Y39370D02*
-X0Y0D01*
 M02*

tests/expects/dxf_rectangle_metric.gtl

@@ -6,15 +6,14 @@ G75*
 %LPD*%
 D10*
 G01*
-X0Y0D02*
+X0Y100000D02*
+G75*
+G01*
+X0Y0D01*
+G01*
 X100000Y0D01*
 G01*
-X100000Y0D02*
 X100000Y100000D01*
 G01*
-X100000Y100000D02*
 X0Y100000D01*
-G01*
-X0Y100000D02*
-X0Y0D01*
 M02*

tests/expects/dxf_rotate.gtl

@@ -25,11 +25,6 @@ X130782Y15428D01*
 G02*
 X124805Y2611I-9397J-3420D01*
 G01*
-X31930Y20924D02*
-G75*
-G03*
-X31930Y20924I-3000J0D01*
-G01*
 X23162Y45543D02*
 G75*
 G02*
@@ -38,4 +33,9 @@ G01*
 X20343Y44517D01*
 G01*
 X23162Y45543D01*
+G01*
+X31749Y21950D02*
+G75*
+G02*
+X31749Y21950I-2819J-1026D01*
 M02*

tests/expects/dxf_save_fill.gtl

@@ -26,11 +26,6 @@ X100000Y10000D01*
 G02*
 X90000Y0I-10000J0D01*
 G01*
-X9171Y50000D02*
-G75*
-G03*
-X9171Y50000I-3000J0D01*
-G01*
 X9171Y75107D02*
 G75*
 G02*
@@ -39,5 +34,10 @@ G01*
 X6171Y75107D01*
 G01*
 X9171Y75107D01*
+G01*
+X9171Y50000D02*
+G75*
+G02*
+X9171Y50000I-3000J0D01*
 G37*
 M02*

tests/expects/dxf_save_line.gtl

@@ -25,11 +25,6 @@ X100000Y10000D01*
 G02*
 X90000Y0I-10000J0D01*
 G01*
-X9171Y50000D02*
-G75*
-G03*
-X9171Y50000I-3000J0D01*
-G01*
 X9171Y75107D02*
 G75*
 G02*
@@ -38,4 +33,9 @@ G01*
 X6171Y75107D01*
 G01*
 X9171Y75107D01*
+G01*
+X9171Y50000D02*
+G75*
+G02*
+X9171Y50000I-3000J0D01*
 M02*

tests/expects/dxf_to_inch.gtl

@@ -25,11 +25,6 @@ X39370Y3937D01*
 G02*
 X35433Y0I-3937J0D01*
 G01*
-X3610Y19685D02*
-G75*
-G03*
-X3610Y19685I-1181J0D01*
-G01*
 X3610Y29570D02*
 G75*
 G02*
@@ -38,4 +33,9 @@ G01*
 X2429Y29570D01*
 G01*
 X3610Y29570D01*
+G01*
+X3610Y19685D02*
+G75*
+G02*
+X3610Y19685I-1181J0D01*
 M02*