string performance optimisation

[sergeevik]

string and regex optimisation

For string:

• create string by ""+char created new every time. If use String.valueOf some string get from java cache (memmory optimisation)
• replace string concationation in cycle on stringbuilder

For regex:

• pattern compile one time and then use multiple times instead compile every time

JsonParser.java
replace readEscape logic with hex data (remove create string and parse it)