7842 - new directory organization

Baremetal is now the default build target and therefore has its sources
at the top-level. Baremetal programs build using the phase-2 Mu toolchain
that requires a Linux kernel. This phase-2 codebase which used to be at
the top-level is now under the linux/ directory. Finally, the phase-2 toolchain,
while self-hosting, has a way to bootstrap from a C implementation, which
is now stored in linux/bootstrap. The bootstrap C implementation uses some
literate programming tools that are now in linux/bootstrap/tools.

So the whole thing has gotten inverted. Each directory should build one
artifact and include the main sources (along with standard library). Tools
used for building it are relegated to sub-directories, even though those
tools are often useful in their own right, and have had lots of interesting
programs written using them.

A couple of things have gotten dropped in this process:
  - I had old ways to run on just a Linux kernel, or with a Soso kernel.
    No more.
  - I had some old tooling for running a single test at the cursor. I haven't
    used that lately. Maybe I'll bring it back one day.

The reorg isn't done yet. Still to do:
  - redo documentation everywhere. All the README files, all other markdown,
    particularly vocabulary.md.
  - clean up how-to-run comments at the start of programs everywhere
  - rethink what to do with the html/ directory. Do we even want to keep
    supporting it?

In spite of these shortcomings, all the scripts at the top-level, linux/
and linux/bootstrap are working. The names of the scripts also feel reasonable.
This is a good milestone to take stock at.

1 files changed, 8 insertions, 36 deletions

diff --git a/README.md b/README.md
index cb096330..83115d14 100644
--- a/README.md
+++ b/README.md
@@ -105,42 +105,6 @@ Use `translate_mu` to build programs for Linux, and `translate_mu_baremetal`
 for running without Linux. The standard libraries are totally separate for the
 two options, so programs for one won't run on the other.
 
-### incomplete tools
-
-There's a prototype live-updating programming environment for a postfix
-language:
-
-```sh
-$ ./translate_mu apps/tile/*.mu
-$ ./a.elf screen
-```
-
-Once generated, ELF binaries can be packaged up with a Linux kernel into a
-bootable disk image. Here's how the postfix environment might look on startup:
-
-```sh
-$ ./translate_mu apps/tile/*.mu  # emit a.elf
-# dependencies
-$ sudo apt install build-essential flex bison wget libelf-dev libssl-dev xorriso
-$ tools/iso/linux a.elf
-$ qemu-system-x86_64 -m 256M -cdrom mu_linux.iso -boot d
-```
-
-<img alt='screenshot of Mu running on Qemu' src='html/20201114-qemu.png'>
-
-The disk image also runs on [any cloud server that supports custom images](http://akkartik.name/post/iso-on-linode).
-
-Mu also runs on the minimal hobbyist OS [Soso](https://github.com/ozkl/soso).
-(Requires graphics and sudo access. Currently doesn't work on a cloud server.)
-
-```sh
-$ ./translate_mu apps/ex2.mu  # emit a.elf
-# dependencies
-$ sudo apt install build-essential util-linux nasm xorriso  # maybe also dosfstools and mtools
-$ tools/iso/soso a.elf  # requires sudo
-$ qemu-system-i386 -cdrom mu_soso.iso
-```
-
 ## Syntax
 
 The entire stack shares certain properties and conventions. Programs consist
@@ -200,6 +164,14 @@ If you're still reading, here are some more things to check out:
   SubX](subx_bare.md) without any syntax sugar.
 
 - [Some 2-minute videos demonstrating Mu programs](https://archive.org/details/@kartik_agaram).
+  Many of them involve this prototype live-updating programming environment
+  for a postfix language that I might work on again one day:
+
+  ```sh
+  $ cd linux
+  $ ./translate tile/*.mu
+  $ ./a.elf screen
+  ```
 
 - [How to get your text editor set up for Mu and SubX programs.](editor.md)