Add Database::tryExec()

[kcowolf]

Similar to Statement::tryExecuteStep(), allows calls to sqlite3_exec() with the caller assuming responsibility for checking and handling the returned status.

[coveralls]

Coverage remained the same at 100.0% when pulling 1d0d8fe on kcowolf:master into adb7e7c on SRombauts:master.

[SRombauts]

Hello!
I find this to be useful. But I am really hesitant about the name, since it doesn't convey exactly the fact that it doesn't deal with exceptions (quite the opposite with the "try" keyword)
Or is this a sort of naming convention I am unaware of?

[kcowolf]

I was trying to follow Statement::tryExecuteStep(), which similarly doesn't throw exceptions (compared to Statement::executeStep and Statement::exec, which do).

Also, C# has some "Try" functions which behave similarly. For example, int.TryParse() versus int.Parse(). int.TryParse() returns false if the string can't be parsed as an integer, while int.Parse() throws an exception. https://stackoverflow.com/questions/467613/parse-v-tryparse

I'd be fine with renaming it if you prefer, though. It just made sense to me based on the above.

[SRombauts]

Then it's settled, thank you!