String koan

[FayeAlephNil]

Covers

• String creation
• String concatenation
• Counting strings characters and getting them
• Difference between chars and strings
• Substrings
• string/join w/ and w/o separators
• string/split-lines
• .indexOf and .lastIndexOf
• string/trim
• char? and string?
• blank?

Thanks for creating this tool btw, really helped me refresh on clojure after having not used it for a while

[trptcolin]

Hey, thanks a bunch for tackling this! I'm sorry it's taking me so long to review it. Work, parenting, excuses, etc.

Just 2 requests:

• the additional gitignore entries seem fine and especially useful for beginners. I'd just like to delete the duplicate entries that are above the auto-generated ones. If you don't get to it in the next day or so I can go ahead & merge, then delete them later.
• There are some typos in the string loan descriptions (e.g. seperate -> separate) - same deal w/ those, if you have time I'd welcome help but I'll merge & cleanup later if not.

The file renames will make it tricky for anyone to merge in the latest changes. Not sure how common that use case is, but it's a problem that we have in general w/ this ordering scheme & adding koans in the middle. I'm fine leaving this re-ordering in place but if you have ideas on a less invasive ordering scheme for the future, I'd love to hear it!

Upgrading the Clojure version isn't related to the main goal of this PR, but I agree it's a good idea - :+1:

Thanks again, and sorry for the delay!

[FayeAlephNil]

That should fix those small problems. As far as the file renames I don't have a good solution, you'd have to fix that in the koan lein plugin with some system, and I don't have any ideas

[trptcolin]

Awesome, thanks!