Generate developer docs with Sphinx

An effort was started some time ago to consolidate all internal
documentation in the git tree. However, this was just an accumulation of
files in various formats without any strucutre or way to browse it,
which results in no one even knowing that we have docs here.

This converts most of the files to restructuredtext and uses Sphinx to
generate an HTML browsable user manual (with a table of content and a
first attempt to put things in a global hierarchy).

There are almost no changes to the documentation content in this commit
(some obviously obsolete things were removed). The plan is to get the
toolchain up and running to make these docs easily available, and only
then see about improving the content. We can migrate some things off the
wiki and website, and rework the table of contents to have some more
hierarchy levels because currently it's a bit messy.

Change-Id: I924ac9dc6e753887ab56f18a09bdb0a1e1793bfd
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4370
Reviewed-by: Niels Sascha Reedijk <[email protected]>

docs/develop/servers/app_server/DebugTools.rst

@@ -0,0 +1,20 @@
+Debug Utility functions
+#######################
+
+These functions are used to make print-based debugging easier.
+
+- BString TranslateStatusToBString(status_t value)
+- BString TranslateColorSpaceToBString(color_space value)
+- BString TranslateMessageCodeToBString(int32 value)
+- BString TranslateStatusToBString(status_t value)
+- BString TranslateColorSpaceToBString(color_space value)
+- BString TranslateMessageCodeToBString(int32 value)
+- const char \* TranslateStatusToString(status_t value)
+- const char \* TranslateColorSpaceToString(color_space value)
+- const char \* TranslateMessageCodeToString(int32 value)
+
+All of these functions are essentially big switch() statements which
+assign an appropriate string for the passed parameter and return the
+assigned string. This way the string can be printed or otherwise
+easily used.
+