fix #13
+ add FUNCTION_STMT in ast.h, 'function()' and 'end' now are not statements
* use MakeBlockStatement instead of MakeLoopStatement
+ add AstStatement.sub_print_count to insert semicolon in the right place (not before first stmt of a block)
fix #14
* buffer overflow when disassemble with a long constant
+ add StringBuffer* StringBuffer_newBySize(int size)
test case for #13