Add -b parameter to samtools merge manpage
Update samtools.1
Match style for FILE option
Alternate syntax for samtools merge.

Providing a FILE to the -b option for samtools merge overrides any file selection made at the command line, I have added an alternative syntax line in the documentation to try and clarify this.
Alternate syntax for samtools merge in stderr message
Clarify list is not a literal
Match samtools merge manpage and stderr syntax
Add code to separate out stdout and stderr in testing

Previously the output of these was merged by redirection.

Signed-off-by: Martin O. Pollard <mp15@sanger.ac.uk>
Make merge take union of commandline and -b inputs and test merge code

Make merge command take union of command line input file and those listed in
-b's fofn.
Add tests for merge code

Signed-off-by: Martin O. Pollard <mp15@sanger.ac.uk>
Merge branch 'patch-1' of https://github.com/SamStudio8/samtools into merge_unioninput

Adjust patch to fit in with changes made to usage.
Reformat usage for 80 columns

Also make usage()'s parameter directly understandable.
(Otherwise, which one is true and which is false?!)
To free unaccounted_header_name, it must have been malloced

Avoid strsep(3), which is not particularly portable.
Make merge_usage()'s parameter directly understandable
Merge merge input and doc fixes, test stdout/stderr fixes (PRs #188, #202)