Render source code using python functions instead of Jinja templates

- Type checker can help out when updating the functions
- The output formatting is much more readable now

MANIFEST.in

@@ -1,3 +1,2 @@
 recursive-include robotpy_build/pybind11/include *.h
-recursive-include robotpy_build/autowrap *.j2
 recursive-include robotpy_build/include *.h

robotpy_build/autowrap/buffer.py

@@ -0,0 +1,45 @@
+import io
+import contextlib
+import inspect
+
+
+class RenderBuffer:
+    def __init__(self) -> None:
+        self._buffer = io.StringIO()
+
+        self._indent = ""
+        self._indentlen = 0
+
+    def getvalue(self) -> str:
+        return self._buffer.getvalue()
+
+    def rel_indent(self, spaces: int):
+        self._indentlen += spaces
+        self._indent = " " * self._indentlen
+
+    @contextlib.contextmanager
+    def indent(self, spaces: int = 2):
+        self._indentlen += spaces
+        self._indent = " " * self._indentlen
+        try:
+            yield
+        finally:
+            self._indentlen -= spaces
+            self._indent = " " * self._indentlen
+
+    def writeln(self, s: str = ""):
+        if not s:
+            self._buffer.write("\n")
+        else:
+            for line in s.splitlines(False):
+                if line:
+                    self._buffer.write(f"{self._indent}{line}\n")
+                else:
+                    self._buffer.write("\n")
+
+    def write_trim(self, s: str):
+        for line in inspect.cleandoc(s).splitlines(False):
+            if line:
+                self._buffer.write(f"{self._indent}{line}\n")
+            else:
+                self._buffer.write("\n")