IParser: Use long long int

[WeiqunZhang]

• Use long long int as the underlying integer data type in IParser.

• Extend number format to include 3e9, 2.34e6, 1'000'000, etc.

[WeiqunZhang]

For this test, https://github.com/WeiqunZhang/amrex-devtests/blob/main/iparser_long/main.cpp

    {
        std::vector<std::string> vs{"1'234'567'890'123", // good
                                    "-1000",             // good
                                    "5e2",               // good
                                    "5.400e4",           // good
                                    "-5.4e2",            // good
                                    ".123e5",            // good
                                    "0.123e5",           // good
                                    "5.43e2",            // good
                                    "1234e0",            // good         
                                    "1234.567e3",        // good
                                    "3e-4",              // bad
                                    "5.432e2",           // bad
                                    "10000e-3",          // bad
                                    "3.14"};             // bad
        for (auto const& s : vs) {
            std::cout << "s = " << std::setw(18) << s;
            try {
                IParser iparser(s);
                auto exe = iparser.compile<0>();
                auto i = exe();
                std::cout << "    i = " << i << "\n";
            } catch (std::runtime_error const& e) {
                std::cout << "    error: " << e.what() << '\n';
            }
        }
    }

produces

s =  1'234'567'890'123    i = 1234567890123
s =              -1000    i = -1000
s =                5e2    i = 500
s =            5.400e4    i = 54000
s =             -5.4e2    i = -540
s =             .123e5    i = 12300
s =            0.123e5    i = 12300
s =             5.43e2    i = 543
s =             1234e0    i = 1234
s =         1234.567e3    i = 1234567
s =               3e-4    error: syntax error in IParser expression "3e-4"
s =            5.432e2    error: 5.432e2 is not an integer in IParser expression "5.432e2"
s =           10000e-3    error: syntax error in IParser expression "10000e-3"
s =               3.14    error: 3.14 is not an integer in IParser expression "3.14"

[WeiqunZhang]

We could allow 10000e-3, if people want it.

[atmyers]

Why is the former reasonable but the latter not?

[WeiqunZhang]

A typo.