Merge branch 'develop-clean-c99'. Close #453.

**Description**

In our effort to comply with our NASA Class D requirements, our code must abide
by a style guide. In particular, the C99 library does not conform to our rules,
so it should be amended.

Full compliance is hard to establish, especially for more opinionated rules
pertaining to simplicity. Further issues may need to address style conformance
concerns.

**Type**

- Management: conformance with new requirement.

**Additional context**

None.

**Requester**

- Ivan Perez

**Method to check presence of bug**

Not applicable (not a bug).

**Expected result**

All Copilot code conforms to the following rules:
- All comments are line comments except for compiler options, language pragmas,
  and annotations/warnings/deprecations.
- Contiguous block comments are alphabetized, given one per line, and
  horizontally aligned.
- Never leave a white spaces between a value and a comma.
- Do not include TODOs or FIXMES.
- A where keyword always stands alone on a line (except for
  class/instance/data/module declarations).
- No more than one empty line between definitions.
- No horizontal lines to separate sections in code.
- No trailing spaces.
- All exports should be explicit.
- All imports should be explicit.
- Imports should be grouped, sorted, alphabetized, and aligned.
- The standard indendation is 2 spaces.
- Always leave a space after a comma.
- Do not require unnecessary pragmas.
- Do not add unnecessary imports.
- Do not include redundant brackets, except where the brackets are meant to
  communicate a conceptual unit.
- Do not include redundant `$`.
- Whenever possible, prefer simpler solutions and expressions.
- Use haddock formatting to capture copyright notices.
- Prefer guards to multiple nested if-then-else.
- Variable names should be camelCase.
- Code should compile without warnings.

**Solution implemented**

Make all code comply with the rules above.

**Further notes**

None.

copilot-c99/CHANGELOG

@@ -1,3 +1,6 @@
+2023-09-07
+        * Clean code. (#453)
+
 2023-07-07
         * Version bump (3.16). (#448)
         * Introduce testing infrastructure. (#413)

copilot-c99/copilot-c99.cabal

@@ -51,9 +51,10 @@ library
 
   exposed-modules         : Copilot.Compile.C99
 
-  other-modules          : Copilot.Compile.C99.Translate
+  other-modules          : Copilot.Compile.C99.Expr
+                         , Copilot.Compile.C99.Type
                          , Copilot.Compile.C99.Error
-                         , Copilot.Compile.C99.Util
+                         , Copilot.Compile.C99.Name
                          , Copilot.Compile.C99.CodeGen
                          , Copilot.Compile.C99.External
                          , Copilot.Compile.C99.Compile

copilot-c99/src/Copilot/Compile/C99.hs

@@ -6,5 +6,6 @@ module Copilot.Compile.C99
   , mkDefaultCSettings
   ) where
 
-import Copilot.Compile.C99.Compile
-import Copilot.Compile.C99.Settings
+-- Internal imports
+import Copilot.Compile.C99.Compile  ( compile, compileWith )
+import Copilot.Compile.C99.Settings ( CSettings (..), mkDefaultCSettings )