refactor: convert camelCase to snake_case (#37)

Purposes:
1. To match typical modern Python coding styles (recommended by PEP 8)
2. To prepare for argparse usage, which uses snake_case for default dests

Via https://ast-grep.github.io/, with rule:

```
id: _
language: python

rule:
  pattern: $ID
  kind: identifier
  all:
  - regex: '^[^A-Z]'  # not PascalCase
  - regex: '[a-z][A-Z]'  # has camelCase transition

  not:
    any:
    # backcompat (part of cog module API)
    - regex: ^sOut$
    - inside:
        kind: attribute
        has:
          field: object
          regex: \.cogmodule$

    # unittest methods
    - regex: ^assert
    - regex: ^setUp$
    - regex: ^tearDown$
    - regex: ^addCleanup$

transform:
  ID_SNAKE:
    convert:
      source: $ID
      toCase: snakeCase
  UNDERSCORE:
    replace:
      source: $ID
      replace: '^(_)?.*'
      by: '$1'

fix: $UNDERSCORE$ID_SNAKE
```

plus manual review of all changes

cogapp/makefiles.py

@@ -2,10 +2,10 @@
 
 import os.path
 
-from .whiteutils import reindentBlock
+from .whiteutils import reindent_block
 
 
-def makeFiles(d, basedir="."):
+def make_files(d, basedir="."):
     """Create files from the dictionary `d` in the directory named by `basedir`."""
     for name, contents in d.items():
         child = os.path.join(basedir, name)
@@ -14,14 +14,14 @@ def makeFiles(d, basedir="."):
             if isinstance(contents, bytes):
                 mode += "b"
             with open(child, mode) as f:
-                f.write(reindentBlock(contents))
+                f.write(reindent_block(contents))
         else:
             if not os.path.exists(child):
                 os.mkdir(child)
-            makeFiles(contents, child)
+            make_files(contents, child)
 
 
-def removeFiles(d, basedir="."):
+def remove_files(d, basedir="."):
     """Remove the files created by `makeFiles`.
 
     Directories are removed if they are empty.
@@ -32,6 +32,6 @@ def removeFiles(d, basedir="."):
         if isinstance(contents, (bytes, str)):
             os.remove(child)
         else:
-            removeFiles(contents, child)
+            remove_files(contents, child)
             if not os.listdir(child):
                 os.rmdir(child)