dialyzer: Add support for multiple PLTs

This new feature is able to take multiple PLTs, merge them during the
start of the analysis, and work from there. This works provided that
the PLTs do not have a module with the same name appearing in more
than one PLT.

The PLTs are created in the usual way:

    dialyzer --build_plt --output_plt PLT_1  FILES_TO_INCLUDE
    ...
    dialyzer --build_plt --output_plt PLT_N  FILES_TO_INCLUDE

and then can be used in either of the following ways:

    dialyzer  FILES_TO_ANALYZE  --plts PLT_1 ... PLT_N
or:
    dialyzer --plts PLT_1 ... PLT_N -- FILES_TO_ANALYZE

(Note the -- delimiter in the second case)

1 files changed, 9 insertions, 3 deletions

diff --git a/lib/dialyzer/doc/manual.txt b/lib/dialyzer/doc/manual.txt
index 470ddd6c73..d9cb52f722 100644
--- a/lib/dialyzer/doc/manual.txt
+++ b/lib/dialyzer/doc/manual.txt
@@ -123,9 +123,10 @@ The exit status of the command line version is:
 
 
 Usage: dialyzer [--help] [--version] [--shell] [--quiet] [--verbose]
-		[-pa dir]* [--plt plt] [-Ddefine]* [-I include_dir]* 
-		[--output_plt file] [-Wwarn]* [--src]  [--gui | --wx]
-		[files_or_dirs] [-r dirs] [--apps applications] [-o outfile]
+		[-pa dir]* [--plt plt] [--plts plts] [-Ddefine]*
+                [-I include_dir]* [--output_plt file] [-Wwarn]*
+                [--src]  [--gui | --wx] [files_or_dirs] [-r dirs]
+                [--apps applications] [-o outfile]
 		[--build_plt] [--add_to_plt] [--remove_from_plt]
 		[--check_plt] [--no_check_plt] [--plt_info] [--get_warnings]
                 [--no_native]
@@ -167,6 +168,10 @@ Options:
    --plt plt
        Use the specified plt as the initial plt (if the plt was built 
        during setup the files will be checked for consistency)
+   --plts plts
+       Merges the specified plts to create the initial plt -- requires
+       that the plts are disjoint (i.e., do not have any module
+       appearing in more than one plt)
    -Wwarn
        A family of options which selectively turn on/off warnings
        (for help on the names of warnings use dialyzer -Whelp)
@@ -294,6 +299,7 @@ Option   :: {files,          [Filename :: string()]}
 	  | {defines,        [{Macro :: atom(), Value :: term()}]}
 	  | {from,           src_code | byte_code} %% Defaults to byte_code
 	  | {init_plt,       FileName :: string()} %% If changed from default
+          | {plts,           [FileName :: string()]} %% If changed from default
 	  | {include_dirs,   [DirName :: string()]} 
 	  | {output_file,    FileName :: string()}
 	  | {output_plt,     FileName :: string()}