Improve Logging and Logging Documentation

[scottfurry]

rsgain: 3.6
platform: x86_64 (AMD) Linux
kernel: 6.1.140-gentoo-x86_64
gcc: 14.3.0 p8

README does not explicitly state where log files are stored. After three attempted runs resulting in segmentation faults, it was found rsgain was aborting execution because of a full volume (no space left on HDD). Also found was rsgain writing csv files on a per-album basis. For a large collection, this will result in a ridiculous number of csv files buried in album directories.

Request the following:
a) improve documentation to state clearly default log file output;
b) improve execution to gracefully abort scan should problems be found when writing log file(s);
c) allow user to redirect log output to another location; and
d) allow user to redirect log to a single csv file.