Add doxygen conf

Adding doxyconf as rA default conf for doxygen and for people if they
wish to build their doc.
Adding tools/build_doc to check app for building doc and to update
version number in documentation.
Fix few typo in src

tools/build_doc.pl

@@ -0,0 +1,72 @@
+#!/usr/bin/perl
+# building documentation using doxygen and updation versionning number
+use strict;
+use File::Basename;
+
+my $sDocFile = "doxyconf";
+my $outputdir = "doc/doxygen";
+my @line = ();
+my $repoversion;
+my $gitversion;
+my $doxyversion;
+my $chked;
+
+my($filename, $dir, $suffix) = fileparse($0);
+chdir "../$dir"; #put ourself like was called in tools
+
+#checking for doxygen
+open PIPE,"doxygen --version |" or die $!;
+@line = grep { /\d.\d.\d/ } <PIPE>;
+$doxyversion = $line[0];
+print "doxyversion = [ $doxyversion ]\n";
+if($doxyversion eq ""){
+	die "Please install doxygen to proceed";
+}
+close PIPE;
+
+#cheking for git cli
+open PIPE,"git --version |" or die $!;
+@line = grep { /\d.\d.\d.\d/ } <PIPE>;
+$gitversion = $line[0];
+$gitversion =~ s/[^\d.\d.\d.\d]//g;
+print "doxyversion = [ $gitversion ]\n";
+if($gitversion eq ""){
+	die "Please install git to proceed";
+}
+close PIPE;
+
+open PIPE,"git rev-parse --short HEAD |" or die $!;
+@line = grep { /\w/ } <PIPE>;
+$repoversion = $line[0];
+print "Git hash is : $repoversion";
+close PIPE;
+
+unless(-r "$outputdir"){
+	mkdir "$outputdir" or die "Can't create output directory for documentation (outdir=$outputdir)\n";
+}
+
+die "$sDocFile doesn't seem to exist or coudldn't be read" unless(-r "$sDocFile");
+print "Updating doxygen file version (doxyconf=$sDocFile)\n";
+open FHIN,"$sDocFile" || die "couldn't openfile/create $sDocFile \n";
+open FHOUT,">doxyconf.tmp" || die "couldn't openfile/create doxyconf.tmp \n";
+while(<FHIN>){ 
+	if(($chked&1)==0 && $_ =~ /^PROJECT_NUMBER/) {
+		@line = split(" ",$_);
+		print FHOUT "PROJECT_NUMBER  = $repoversion";
+		print "Updated project number\n";
+		$chked &=1;
+	}
+	elsif(($chked&2)==0 && $_ =~ /^OUTPUT_DIRECTORY/){
+		print FHOUT "OUTPUT_DIRECTORY  = $outputdir";
+		print "Updated output dir\n";
+		$chked &=2;
+	}
+	else { print FHOUT $_; }
+}
+close FHIN;
+close FHOUT;
+unlink $sDocFile;
+rename "doxyconf.tmp", $sDocFile;
+
+print "Building doc\n";
+system("doxygen doxyconf");