Big project dir refactor

* split into multi member workspace in preparation for a no_std core
* env and posix stuff neatly crammed into a seperate shell project
* some pokes at interactive-devel.f
* updated ci
* removed 'l' shortcut for 'load' and update docs
* remove out of date readme content
* updated tests
* more sensible cond implementation and extra tests
* substr stdlib function with tests

Signed-off-by: Ava Affine <ava@sunnypup.io>

shell/Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "flesh-shell"
+version = "0.4.0"
+authors = ["Ava Affine <ava@sunnypup.io>"]
+edition = "2021"
+
+[[bin]]
+name = "flesh"
+path = "src/main.rs"
+
+[dependencies]
+# used in config (src/run.rs)
+dirs = "3.0"
+# these two are used in src/bin/relish.rs to manage a prompt
+nu-ansi-term = "0.47.0"
+reedline = "0.17.0"
+# used by main shell to update console dimensions
+termion = "2.0.1"
+# these two used in posix shell layer (src/stl/posix.rs)
+nix = { version = "0.26.2", optional = true }
+libc = { version = "0.2.144", optional = true }
+flesh-core = { path = "../core", features = ["implicit-load"]}
+
+[features]
+default = ["posix"]
+posix = ["dep:nix", "dep:libc"]