[SCHEMA] Reorganize schema code into a package

tools/schemacode/MANIFEST.in

@@ -0,0 +1 @@
+include versioneer.py

tools/schemacode/README.md

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+# schemacode
+
+A Python library for working with the BIDS schema.

tools/schemacode/pyproject.toml

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+[build-system]
+requires = ["setuptools", "wheel"]
+
+[tool.black]
+line-length = 99
+target-version = ['py37']
+include = '\.pyi?$'
+exclude = '''
+(
+  /(
+      \.eggs         # exclude a few common directories in the
+    | \.git          # root of the project
+    | \.github
+    | \.hg
+    | \.pytest_cache
+    | _build
+    | build
+    | dist
+  )/
+  | get_version.py
+  | versioneer.py
+  | schemacode/info.py
+  | schemacode/_version.py
+)
+'''
+
+[tool.isort]
+profile = "black"
+multi_line_output = 3