refactor: rename getBlockElements to more correct getBlockNodes
refactor: simplify trim fn now that IE9 has String#trim
perf(jqLite): don't check isString many times in constructor

Note: no significant perf gain in Chrome
style(jqLite): remove MiskoCode(tm)
refactor(jqLite): don't look up the entry needlessly
perf(jqLite): don't use String#split in on() unless we need it
perf(jqLite): microoptimization in chaining fn

note: no siginificant difference observed in macrobenchmarks, so this is just to make
me feel better :)
refactor(shallowCopy): microoptimization