Issue 56. Performance patch from dewvinci & tobias hoehman.
Issue 56. Performance patch from dewvinci & tobias hoehman.

This speeded up parsing of the short string by about 60%, and the long string
by nearly 10%. Weirdly it slowed down the writing of the long string by about
5% in my measurements. I don't know where this slowdown is from, as the patch
doesn't touch the writer at all. But the speedup in reading is so great that I
decided to apply it anyway, given parsing is (presumably) the most common
action.

Here's a CSV snippet showing the stats:

what,vanilla,string part,%,num part,%,whole patch,%
parse short,18251.975631,18795.895138,-2.98%,29248.981869,-60.25%,29589.446208,-62.12%
parse long,659.113859,652.571277,0.99%,668.452264,-1.42%,661.46303,-0.36%
write short,31847.410782,31655.124528,0.60%,28416.693767,10.77%,28737.951353,9.76%
write long,904.490641,892.851532,1.29%,839.204874,7.22%,861.332977,4.77%
,,,-0.10%,,-43.68%,,-47.94%

puvanarajan/json-framework,sporttech/json-framework,stig/json-framework,nett55/json-framework,adonoho/json-framework,cnbin/json-framework,duanhjlt/json-framework,Jawbone/json-framework,hkg36/SBJson_amenmod,HSFGitHub/json-framework,adamvduke/json-framework,adamvduke/json-framework,Liaojinghui/json-framework,0xc010d/json-framework,ramoslin02/json-framework,hkg36/SBJson_amenmod,AbelSu131/json-framework,0xc010d/json-framework,AlexanderMazaletskiy/json-framework,SinnerSchraderMobileMirrors/json-framework