[auto build] add timestamps in logs, format Python code and change config

* move compile_lilypond_test.py and its submodules in a subdirectory;
* use a configuration variable rather than an environment variable for
LilyPond git repo directory;
* make email sender address configurable;
* code formatting: add space before parentheses in Python code;
* slightly improve exceptions logic;
* add timestamps in build log.
[auto build] further fixes and allow disabling of email sending

When lilypond-patchy-staging is run very frequently (say every one to
three hours), emails just saying that no build has been done nor failed
are undesirable, so a configuration option notify_non_action has been
added.
Begin GOP 2.
incomplete notes for GOP 2-1 gnu.
finish adding GOP 2-1 gnu stuff.
Fix test-patches and lilypond-patchy-staging configuration
Updates from email contact with GNU maintainers.
Begin GLISS notes.
Move compile_lilypond_test default configuration into Python module

This has some advantages over an external default config file:
- lilypond-patchy-staging no longer has to be run in its containing
directory at first run for creating the configuration file;
- the default configuration is loaded at each run, so existing
setups no longer break because new options are added.
More GOP2-1 updates
Summarization of GOP2-0 emails.
GOP 2-2 stable releases
GOP 2-2: add assumption that regtests are good
GOP2-2: additional notes.
GOP: more GNU policies
GOP revisions for 2.16 releases.
GOP clarify 2-2b as stable 2.16 releases
GOP 2-2b clarifications
GOP 2-1 updates
Adds Reinholds LAC2010 paper to pdfs