Title template (#194)

* added template option and validation

* update comment link to element list

* get author info when fetching video info

* added template elements to video object

* minor function naming changes

* better exit message for template error

* changed template elements for better substitution

* implemented video title template

* removed trailing decimals on duration

* added template description

* removed hashing from uniqueId
removed debug logger.warn()

* fixed typos in default template
added elements to template fail message

* moved ffmpeg version logging to verbose

README.md

@@ -19,6 +19,11 @@ This release would not have been possible without the code and time contributed
 - [Università della Calabria][unical]: fork over at https://github.com/peppelongo96/UnicalDown
 
 ## What's new
+### v2.2
+
+- Added title template
+
+### v2.1
 
 - Major code refactoring (all credits to @lukaarma)
 - Destreamer is now able to refresh the session's access token. Use this with `-k` (keep cookies) and tick "Remember Me" on login.
@@ -138,6 +143,26 @@ https://web.microsoftstream.com/video/xxxxxxxx-aaaa-xxxx-xxxx-xxxxxxxxxxxx
         -dir=videos/lessons/week2"
 ```
 
+### Title template
+The `-t` option allows users to input a template string for the output file names.
+In the template you have to use 1 or more of the following special sequence that will be substituted at runtime.
+The special sequences must be surrounded by curly brackets like this '{title} {publishDate}'
+
+- `title`: the video title
+- `duration`: the video duration in HH:MM:SS format
+- `publishDate`: the date when the video was first published in YYYY-MM-DD format
+- `publishTime`: the time when the video was first published in HH:MM:SS format
+- `author`: the video publisher's name
+- `authorEmail`: the video publisher's email
+- `uniqueId`: a (almost) unique ID generated from the video informations
+
+Example -
+```
+Input:
+-t '{title} - {duration} - {publishDate} - {publishTime} - {author} - {authorEmail} - {uniqueId}'
+Expected filename:
+This is an example - 0:16:18 - 2020-07-30 - 10:30:13 - lukaarma - example@domain.org - #3c6ca929.mkv
+```
 
 ## Expected output