Some decluttering of the top-level directory.

Details:
- Relocated 'mpi_test' directory to test/mpi_test.
- Relocated 'so_version' and 'version' files from top-level directory to
  'build' directory.
- Updated build/bump-version.sh script to accommodate relocation of
  'version' file to 'build' directory.
- Updated configure script to accommodate relocation of 'so_version'
  file to 'build' directory.
- Updated INSTALL file to replace pointers to blis-devel mailing list
  with a pointer to docs/Discord.md.
- Updated RELEASING file to contain a reminder to consider whether the
  so_version file should be updated prior to the release.

INSTALL

@@ -17,11 +17,14 @@ viewing the file over GitHub via a web browser:
 This document will always contain the most up-to-date information related
 to instantiating a BLIS library from the framework source code. If you have
 any further questions or wish to provide feedback, please contact the BLIS
-community by posting your message to the BLIS developer's mailing list:
+community by either by joining our Discord community! Instructions for
+joining may be found in:
 
-  https://groups.google.com/d/forum/blis-devel
+  docs/Discord.md
 
-Thanks for your interest in the BLIS framework!
+or in rendered form at:
+
+  https://github.com/flame/blis/blob/master/docs/Discord.md
 
-Field Van Zee
+Thanks for your interest in the BLIS framework!
 

RELEASING

@@ -7,38 +7,42 @@ Here are the steps to follow to create a new release (version) of BLIS:
 
    If there are any commits upstream, merge them as appropriate.
 
-2. Verify that the code builds properly.
+2. Consider whether the so_version should be updated (via the so_version
+   file in the 'build' directory) due to any ABI changes since the previous
+   version. If so, commit that change now.
+
+3. Verify that the code builds properly.
 
    $ ./configure auto; make
 
-3. Verify that the code passes BLIS and BLAS tests:
+4. Verify that the code passes BLIS and BLAS tests:
 
    $ make check           # BLIS testsuite (fast) + BLAS test drivers
    $ make checkblis       # BLIS testsuite (full ex. mixed-datatype)
    $ make checkblis-md    # BLIS testsuite (mixed-datatype only)
    $ make checkblis-salt  # BLIS testsuite (fast + salt)
 
-4. Draft a new announcement to blis-devel, crediting those who
+5. Draft a new announcement to blis-devel, crediting those who
    contributed towards this version by browsing 'git log'.
 
-5. Update CREDITS file if 'git log' reveals any new contributors.
+6. Update CREDITS file if 'git log' reveals any new contributors.
 
-6. Update docs/ReleaseNotes.md file with body of finalized announcement
+7. Update docs/ReleaseNotes.md file with body of finalized announcement
    and the date of the release.
 
-7. Commit changes from steps 5 and 6.
+8. Commit changes from steps 5 and 6.
 
-8. Bump the version number:
+9. Bump the version number:
 
    $ ./build/bump-version.sh "0.3.2"
 
    This will result in two new commits: a version file update and a CHANGELOG
    file update.
 
-9. Push the new commits and new tag associated with the new version:
+10. Push the new commits and new tag associated with the new version:
 
    $ git push
    $ git push --tag
 
-10. Send finalized announcement to blis-devel.
+11. Send finalized announcement to blis-devel.
 

build/bump-version.sh

@@ -98,10 +98,10 @@ main()
 	# The name of the CHANGELOG file.
 	changelog_file='CHANGELOG'
 
-	# The name of the default version file.
-	version_file_def='version'
+	# The name and location of the default version file.
+	version_file_def='build/version'
 
-	# The name of the specified version file.
+	# The name and location of the specified version file.
 	version_file=''
 
 	# Strings used during version query.

configure

@@ -2346,10 +2346,6 @@ main()
 	# of the distribution and the directory in which we are building.
 	cur_dirpath="."
 
-	# The file in which the version string is kept.
-	version_file="version"
-	version_filepath="${dist_path}/${version_file}"
-
 	# The name of and path to the directory named "build" in the top-level
 	# directory of the source distribution.
 	build_dir='build'
@@ -2431,9 +2427,13 @@ main()
 
 	# -- Version-related --
 
+	# The file in which the version string is kept.
+	version_file="version"
+	version_filepath="${build_dirpath}/${version_file}"
+
 	# The shared library (.so) version file.
 	so_version_file='so_version'
-	so_version_filepath="${dist_path}/${so_version_file}"
+	so_version_filepath="${build_dirpath}/${so_version_file}"
 
 	# The major and minor/build .so version numbers.
 	so_version_major=''