Typo fixes and thread/asynchronous IO safety.

Numerous changes to src/stdlib_logger.f90:
1. Changed `Rrea_...` to `read_...`
2. Shortened several long lines, mostly those longer than 80 characters
3. Added buffer and len_buffer to logger_type(?)
4. Changed output so that instead of multiple writes of individual strings there
   is a single write of a single string formatted by inserting new_line calls.

[ticket: X]

Author: wclodius2