ENH: support true/false, yes/no values for FOAM_ABORT (#1896)

- consistent with FOAM_SIGFPE etc.

- centralize code as error::useAbort() static function to avoid
  scattering the logic throughout the code.

ENH: also accept "0" and "1" string values for Switch

- not the normal path for Switch input (eg, from a dictionary), but
  consistent with bool definitions and simplifies string parsing.

  This means that `FOAM_SIGFPE=1 application` will now also work.

etc/bashrc

@@ -129,6 +129,10 @@ projectDir="$HOME/OpenFOAM/OpenFOAM-$WM_PROJECT_VERSION"
 # = true | false
 #export FOAM_SETNAN=false
 
+# [FOAM_ABORT] - Treat exit() on FatalError as abort()
+# = true | false
+#export FOAM_ABORT=false
+
 # [FOAM_CODE_TEMPLATES] - dynamicCode templates
 # - unset: uses 'foamEtcFile -list codeTemplates/dynamicCode'
 ##export FOAM_CODE_TEMPLATES="$WM_PROJECT_DIR/etc/codeTemplates/dynamicCode"

etc/cshrc

@@ -131,6 +131,10 @@ set projectDir=`lsof +p $$ |& sed -ne 's#^[^/]*##;\@/'"$projectName"'[^/]*/etc/c
 # = true | false
 #setenv FOAM_SETNAN false
 
+# [FOAM_ABORT] - Treat exit() on FatalError as abort()
+# = true | false
+#setenv FOAM_ABORT false
+
 # [FOAM_CODE_TEMPLATES] - dynamicCode templates
 # - unset: uses 'foamEtcFile -list codeTemplates/dynamicCode'
 ##setenv FOAM_CODE_TEMPLATES "$WM_PROJECT_DIR/etc/codeTemplates/dynamicCode"