0029830: STEPCAFControl_Reader poor performance - quadratic dependence

Various performance improvements in STEP read/write algorithms:
- Search for the  label of a shape or component shape is improved using map mechanism instead of brute force iteration.
- Invariant FindEntities() is moved out of the loop in the method getStyledItem in STEPCAFControl/STEPCAFControl_Writer.cxx.
- A pointer to the end of binders chain is added in Transfer_Binder class to speed up adding a binder to the chain.
- Small fixes are added  to eliminate excess copying of handles, calls of handle DownCasts and so on.

Stack overflow is removed during destruction of STEP model with long chains of Transfer_Binder.
It is possible to use the Draw commands ReadStep and WriteStep to read/write from the session without accessing the disk file (use '.' for the file name).

Performance test cases for STEP reading/writing have been added.

tests/perf/de/begin

@@ -1 +1 @@
-pload XDE
+pload XDE OCAF

tests/perf/de/bug29830_1

@@ -0,0 +1,2 @@
+set use_sharing 1
+source "$dirname/$groupname/$gridname/bug29830_dir/script"

tests/perf/de/bug29830_2

@@ -0,0 +1,2 @@
+set use_sharing 0
+source "$dirname/$groupname/$gridname/bug29830_dir/script"

tests/perf/de/bug29830_3

@@ -0,0 +1,24 @@
+puts "========"
+puts "0029830: Data Exchange, STEPCAFControl_Reader poor performance - quadratic dependence"
+puts "========"
+puts "Test on stack overflow during destructing the STEP model"
+
+set ncomp 1000
+
+box a 1 1 1
+shape co C
+for {set i 0} {$i < $ncomp} {incr i} {
+  tcopy a a1
+  add a1 co
+}
+if [info exists D] {Close D}
+XNewDoc D
+XAddShape D co
+
+puts "Writing STEP model"
+WriteStep D .
+Close D
+
+puts "Destructing model"
+#crash
+newmodel

tests/perf/de/bug29830_dir/script

@@ -0,0 +1,105 @@
+puts "========"
+puts "0029830: Data Exchange, STEPCAFControl_Reader poor performance - quadratic dependence"
+puts "========"
+puts ""
+
+set copy_cmd tcopy
+
+if $use_sharing {
+  set copy_cmd copy
+}
+
+set dx 2
+set dy 4
+set dz 6
+set nx0 20
+set ny 10
+set nz 10
+
+if [info exists D] {Close D}
+if [info exists D1] {Close D1}
+
+for {set npass 1} {$npass <= 2} {incr npass} {
+
+  set nx [expr $nx0 * $npass]
+  puts "Creating assembly of $nx*$ny*$nz boxes"
+  plane a 0 0 0 1 0 0
+  mkface a a 0 3 0 2
+  shape co C
+
+  for {set i 0} {$i < $nx} {incr i} {
+    for {set j 0} {$j < $ny} {incr j} {
+      for {set k 0} {$k < $nz} {incr k} {
+        eval $copy_cmd a a1
+        ttranslate a1 $dx*$i $dy*$j $dz*$k
+        add a1 co
+      }
+    }
+  }
+  XNewDoc D
+  XAddShape D co
+
+  puts "Assigning colors to components"
+  set i 0
+  set j 0
+  set k 0
+  set shlist [explode co]
+  set lab [lindex [XFindComponent D co_1] 0]
+  set taglist [split $lab :]
+  foreach c $shlist {
+    set r [expr ($i%3)/3.]
+    set g [expr ($j%3)/3.]
+    set b [expr ($k%3)/3.]
+    set lab [join $taglist :]
+    XSetColor D $lab $r $g $b
+    incr k
+    if {$k%3 == 0} {
+      incr j
+      if {$j%3 == 0} {
+        incr i
+      }
+    }
+    set taglist "[lrange $taglist 0 end-1] [expr [lindex $taglist end] + 1]"
+  }
+
+  puts "Writing STEP model"
+  chrono cr1 restart
+  WriteStep D .
+  chrono cr1 stop
+  Close D
+
+  puts "Reading STEP model"
+  chrono cr2 restart
+  ReadStep D1 .
+  chrono cr2 stop
+
+  # check one solid with different locations
+  XGetOneShape result D1
+  if $use_sharing {
+    checknbshapes result -face 1
+    checknbshapes result -face [expr $nx*$ny*$nz] -t
+  } else {
+    checknbshapes result -face [expr $nx*$ny*$nz]
+    checknbshapes result -face [expr $nx*$ny*$nz] -t
+  }
+  
+  if {$npass == 2} {
+    XShow D1
+    vfit
+    vsetdispmode 1
+    checkview -screenshot -3d -path ${imagedir}/${test_image}.png
+  }
+  Close D1
+
+  set time_write_$npass [lindex [dchrono cr1 counter "WriteStep_$npass"] end]
+  set time_read_$npass [lindex [dchrono cr2 counter "ReadStep_$npass"] end]
+}
+
+puts "time_write_1=$time_write_1"
+puts "time_write_2=$time_write_2"
+puts "time_read_1=$time_read_1"
+puts "time_read_2=$time_read_2"
+set time_raise_write [expr $time_write_2 / $time_write_1]
+set time_raise_read [expr $time_read_2 / $time_read_1]
+puts "time_raise_write=$time_raise_write"
+puts "time_raise_read=$time_raise_read"