Unexpected number conversion

[sagikazarmark]

People are complaining about unexpected results when converting a string (usually prefixed with 0) to a number type.

The underlying strconv functions are called with 0 base which means it's trying to guess the base from the string.

There is a potential fix in #249, but we should probably document this better (and maybe add some tests/examples too).

Issues:

• Casting a string to int with a 0 in prefix does not work as expected #74
• bug of toInt toInt32 toInt64 #96
• toInt/toInt64 is wrong #112
• the function ToInt sometimes has some mistakes #133
• cast.ToInt("08") returned 0 #147
• cast.ToInt64E("16025123132364928") return 0 #162
• Unexpected results with padded strings #182
• cast toint32 but return zero #202
• cast.ToInt("08") return 0 and so on #214
• ToInt have bad case #216
• why cast.ToInt("08") return 0 then cast.ToInt("07") return 7 ?  #220
• cast.ToUint32("0134444") = 47396 #232
• fix:string to uint64 error #228
• toIntBase10 enforces base 10 conversion #91
• add func Atoi to convert string base 10 #152
• the code「cast.ToInt("08") 」 has unexpected value result #290
• fix:string to uint64 error #228