tup-v0.8 released

[Mike Shal]

Hi all,

I've tagged the latest master as v0.8. This is the first major version bump since 2013 due to the merge of the explicit variants branch, which results in a backwards incompatibility if you use variants. If you don't use variants, you should be unaffected.

Thanks to Pete Moore, data-man, Jose Quinteiro, r-value, Yaling Fang, Prokop Randacek, Lucas Kanashiro, and Bojidar Marinov for your contributions to this release!

Also, huge thanks to those who have donated via GitHub sponsors & Patreon -- it means a lot to have your support.

Here are the notes:

Backwards incompatibility with variants:
 - The FUSE overlay variants have been removed in favor of explicit variants. If you use variants on version v0.7.11 or earlier, you may need to update your Tupfiles. See https://gittup.org/tup/ex_explicit_variants.html for more details.

New features:
 - Variants now supported in Windows.
 - 'import' keyword to set a Tupfile variable to an environment variable.
 - 'tup compiledb' can create a compile_commands.json for third-party tools to see compilation commands.
 - 'tup commandline' shows the commandline used to compile a file.
 - 'tup generate' can support building in a separate build directory (if the project supports building with variants).
 - 'tup generate' can take an output list to limit what the script generates (ie: a partial build script).
 - A single Lua state is now re-used during parsing and doesn't need to be reinitialized for every Lua-based Tupfile.
 - Internal mtime tracking is now at nanosecond resolution (where supported by the OS) instead of 1-second intervals.

Dependency updates:
 - Internal Lua version is now 5.4.6
 - Internal SQLite version is now 3.45.2
 - Internal PCRE version is now PCRE2 10.42 (The internal version is only used by Windows by default)
 - External PCRE dependency is now libpcre2 instead of libpcre (Linux/OSX by default, unless built with CONFIG_TUP_USE_SYSTEM_PCRE=n in which case the internal version is used)

Bug fixes:
 - Fixed a bug that results in tup_entry_rm called on tupid X, which still has refcount=1
 - ^o rules that fail with a monitor autoupdate no longer cause infinite loops
 - Deleted files are now removed from the transient_list.

Thanks everyone!

-Mike