LuaLogging: A simple API to use logging features in Lua

LuaLogging
A simple API to use logging features in Lua. Portuguese version.

## File appender

The file appender can be used to write log messages to a file. It uses Lua I/O routines to do its job.

    function logging.file(filename, [datePattern], [logPattern])

- `filename`:
  The name of the file to be written to. On each call to log a message the file is opened for appending and closed immediately.
  If the file cannot be opened for appending the logging request returns nil and an error message.
- `datePattern`:
  This is an optional parameter that can be used to specify a date pattern that will be passed to the `os.date` function to compose the filename.
  This is useful to create daily or monthly log files. If the user wants to create one log file per day he specifies a `"%Y-%m-%d"` pattern and a filename like `"temp%s.log"`.
- `logPattern`:
  A pattern can be specified to control how the message is written.
  The default value is `"%date %level %message\n"`.

## Example

    require"logging.file"

    local logger = logging.file("test%s.log", "%Y-%m-%d")

    logger:info("logging.file test")
    logger:debug("debugging...")
    logger:error("error!")