`if` is for getting a value, not nec. side-effecty

Since `if` is more of an expression (rather than executed for side-effects), removed the "do-".

Since `when` supplies an implicit `do`, left the "do-", but removed the "else" (given the implicit `do`).
Merge pull request #26 from uvtc/patch-3

`if` is for getting a value, not nec. side-effecty
refined the rules about spacing around brackets of any sort
added a couple of comment style rules
Fix #21 - Remove "Use underscore in filenames..."
Added a few more namespace guidelines.
better formatting/indentation of example

Makes it more clear exactly what the threading macros are getting you.
Merge pull request #30 from uvtc/patch-4

better formatting/indentation of example
Elaborate on literal syntax for sets usage.
Merge pull request #32 from sw1nn/master

Set literal syntax only when values are compile time constants
Add a couple of rules for exceptions.
Discourage the use of Java collections and arrays.
Rephrase rule about empty lines between defs.
Add a rule about the names of conversion functions.
Add a quote by Alan Perlis to the Collections section.
Add a rule about :else in cond and condp.
more clear wording, but also see issue #20
Always require at least one space after ;
Mention the #_ reader macro.
Merge pull request #33 from uvtc/patch-5

more clear wording, but also see issue #20