Create spectroscopy-letters

I've started working from the applied spectroscopy style as mentioned in the summary. 
There are still a few issues, but at least it seems to be compliant to 100% with journal references
Issue: a comma after the date still appears in the book references and I didn't know how to remove it. Probably it works with conditionals...)
Update spectroscopy-letters

Hi there!

I've done the changes as follows:
- .csl in the ID (line 7) but I don't see the extension in the ID codes of other styles...
- Documentation address is now http://www.tandfonline.com/action/authorSubmission?journalCode=lstl20&amp;page=instructions (line 9)
- Both ISSN updated
- and the changes proposed by zuphilip regarding the comma are also done. I tested it and now it looks very nice!

Thank you guys!
Update spectroscopy-letters

Just modified the summary
Update and rename spectroscopy-letters to spectroscopy-letters.csl

OK!
Also removed .csl in the <id>
Update spectroscopy-letters.csl

In Book reference: changed comma to colon between publisher and place
Update spectroscopy-letters.csl

Here I put back on line 108 to <text macro="year-date"/> to at least have the date appear
Also changed in an ID line 10 "applied-spectroscopy" to "spectroscopy letters"
Now I'll see what I cand do with the CSL Editor to improve the style
Update spectroscopy-letters.csl

Now I worked again with the CSL Editor online.
Several issues have been checked and I copy-pasted the whole code again.
Update spectroscopy-letters.csl

In book chapter: 
- switched editors and book title --> seem to be OK
- Tried to move the In prefix to the book title (container-title macro) --> it still appears before the editors
Update spectroscopy-letters.csl

- Switched the position of text variable="In" from the editor to before the book number
- Added <else> code </else> as proposed by zuphilip in the publisher macro
Update spectroscopy-letters.csl

Changed the template name back to applied-spectroscopy
Added name of co-authors who helped me with the code
Update spectroscopy-letters.csl

Added the contributors in their own "contributor" category
Merge pull request #1097 from Tournolive/patch-2

Create spectroscopy-letters