Add trim/0, ltrim/0 and rtrim/0 that trims leading and trailing whitespace (#3056)

tests/jq.test

@@ -1334,6 +1334,26 @@ split("")
 "xababababax"
 [1,7,[1,3,5,7]]
 
+# trim
+# \u000b is vertical tab (\v not supported by json)
+map(trim), map(ltrim), map(rtrim)
+[" \n\t\r\f\u000b", "","  ", "a", " a ", "abc", "  abc  ", "  abc", "abc  "]
+["", "", "", "a", "a", "abc", "abc", "abc", "abc"]
+["", "", "", "a", "a ", "abc", "abc  ", "abc", "abc  "]
+["", "", "", "a", " a", "abc", "  abc", "  abc", "abc"]
+
+trim, ltrim, rtrim
+"\u0009\u000A\u000B\u000C\u000D\u0020\u0085\u00A0\u1680\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u2028\u2029\u202F\u205F\u3000abc\u0009\u000A\u000B\u000C\u000D\u0020\u0085\u00A0\u1680\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u2028\u2029\u202F\u205F\u3000"
+"abc"
+"abc\u0009\u000A\u000B\u000C\u000D\u0020\u0085\u00A0\u1680\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u2028\u2029\u202F\u205F\u3000"
+"\u0009\u000A\u000B\u000C\u000D\u0020\u0085\u00A0\u1680\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u2028\u2029\u202F\u205F\u3000abc"
+
+try trim catch ., try ltrim catch ., try rtrim catch .
+123
+"trim input must be a string"
+"trim input must be a string"
+"trim input must be a string"
+
 indices(1)
 [0,1,1,2,3,4,1,5]
 [1,2,6]

tests/man.test

@@ -602,6 +602,12 @@ combinations(2)
 ["fo", "foo", "barfoo", "foobar", "foob"]
 ["fo","","bar","foobar","foob"]
 
+trim, ltrim, rtrim
+" abc "
+"abc"
+"abc "
+" abc"
+
 explode
 "foobar"
 [102,111,111,98,97,114]