Inherit std::exception for CppSQLite3Exception

[EmosewaMC]

Fixes #13

The following main.cc code catches the CppSQLite3Exception since it now would inherit std::exception

#include "sqlite3.h"
#include "CppSQLite3.h"
#include <string>
#include <iomanip>
#include <iostream>
#include <cassert>

int main() {
	CppSQLite3DB conn;
	try {
		conn.open("test.sqlite");
		conn.compileStatement("select banana from 1");
	} catch (std::exception& e) {
		std::cout << e.what() << std::endl;
	}
	return 0;
}

[EmosewaMC]

to be sure there were no added memory leaks, I used the following program which when run with valgrind has no memory leaks

#include "sqlite3.h"
#include "CppSQLite3.h"
#include <string>
#include <iomanip>
#include <iostream>
#include <cassert>

int main() {
	CppSQLite3DB conn;
	conn.open("test.sqlite");
	try {
		auto stmt = conn.compileStatement("select banana from ff");
		stmt.bind(1, "banana");
	} catch (std::exception& e) {
		std::cout << e.what() << std::endl;
	}
	return 0;
}

test.sqlite being opened and created with the following table

CREATE TABLE ff (banana text_4);

compiled with

g++ -std=c++11 -I. -c CppSQLite3.cpp
gcc -I. -c sqlite3.c
g++ -std=c++11 -I. main.cc CppSQLite3.o sqlite3.o

run with valgrind ./a.out

==24938== Memcheck, a memory error detector
==24938== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==24938== Using Valgrind-3.18.1 and LibVEX; rerun with -h for copyright info
==24938== Command: ./a.out
==24938==
==24938== error calling PR_SET_PTRACER, vgdb might block
SQLITE_RANGE[25]: Error binding string param
==24938== 
==24938== HEAP SUMMARY:
==24938==     in use at exit: 0 bytes in 0 blocks
==24938==   total heap usage: 78 allocs, 78 frees, 618,848 bytes allocated
==24938==
==24938== All heap blocks were freed -- no leaks are possible
==24938==
==24938== For lists of detected and suppressed errors, rerun with: -s
==24938== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

[mqudsi]

Thanks, this looks good.

[mqudsi]

FYI I just pushed an update to correct the destructor signature to include override as a minor fix.

ef9a931