0024722: Move functionality of WOK command wgendoc to OCCT tool gendoc

Command gendoc improved to:
- generate Reference Manual documentation (OCCT classes reference) with option -refman; option -overview can be used for generation of overview documentation;
- generate PDF documents for all User Guides automatically (for files listed in FILES_PDF.txt);
- check availability of third-party tools (Doxygen, Inkscape etc.) and properly report warnings and errors.
- use templates of configuration files for third-party tools instead of their generation. These template files are located in dox/resources folder

Tcl scripts are moved from dox folder to adm.
Doxygen warnings are eliminated.
Moved all auxilary functions to occaux.tcl.
Fixed Reference manual generation on *nix platform.
Fixed PDF generation on *nix platforms.

dox/tutorial/tutorial.md

@@ -1,4 +1,4 @@
- Tutorial {#tutorial}
+ Tutorial {#occt__tutorial}
 =======
 
 @tableofcontents
@@ -52,7 +52,7 @@ This modeling requires four steps:
 
 To create the bottle's profile, you first create characteristic points with their coordinates as shown below in the (XOY) plane. These points will be the supports that define the geometry of the profile.
 
-@figure{/tutorial/images/tutorial_image003.svg}
+@figure{tutorial/images/tutorial_image003.svg}
 
 There are two classes to describe a 3D Cartesian point from its X, Y and Z coordinates in Open CASCADE Technology: