This updates the SBCL build and release process to be more compatible
with distributed development -- to facilitate moving the upstream
repository into Git.
A detailed description of what is going on here is in
doc/GIT-WORKFLOW.md.
Some highlights:
* Drop version.lisp-expr and branch-version.lisp-expr.
* Auto-generate the version at build time using information
from Git, incorporating:
- Last release number.
- Number of commits on origin/master since last release.
- Current branch, if there are commits not on origin/master.
- Number of commits not on origin/master.
- SHA1 id of the last commit.
- Optional -dirty marker.
* Update release.sh to work with Git.
* Make source-distribution.sh exclude the .git directory from tarballs.
* Release tags contain NEWS for that release.
Merge patch from James Bielman fixing self-build under Win32.
... a little bit of an accident ensued; I ran
canonicalize-whitespace on .sh files, which seemed to
work (except on wc.sh) until it scribbled all over
make.sh, confusing the shell interpreter utterly.
... the resulting files have built the system, nevertheless.
