- argList::envExecutable() static method.
This is identical to getEnv("FOAM_EXECUTABLE"), where the name of
the executable has typically been set from the argList construction.
Provides a singleton access to this value from locations that
do not have knowledge of the originating command args (argList).
This is a similar rationale as for the argList::envGlobalPath() static.
- additional argList::envRelativePath() static method.
- make -dry-run handling more central and easier to use by adding into
argList itself.
STYLE: drop handling of -srcDoc (v1706 option)
- replaced with -doc-source for 1712 and never used much anyhow
