(cleanup after rebase/squash conflict resolution introduced some toml…

… problems.)

- Added examples lora_spi_send, lora_spi_receive, and lora_spi_gps. These work on
  several different MCUs. Documentation for building and running is in lora_spi_send.rs.

- Added directory memoryMaps/ and build.rs to simplify linking.

- Added workflow in .github/workflow/rust.yml for checking examples.

- Added reference to examples in README.

Cargo.toml

@@ -72,9 +72,6 @@ stm32l4xx-hal = {version = "^0.6.0", optional = true}
 embedded-hal = {version = "1.0.0-alpha.4" }
 old-e-h      = {version = "0.2.4", package = "embedded-hal" }
 
-[dependencies.radio]
-version = "0.8.1"
-
 [dependencies.embedded-spi]
 version = "0.6"
 default-features = false 
@@ -86,10 +83,6 @@ default-features = false
 #[dev-dependencies.color-backtrace] # this needs std, which causes example build to fail
 #color-backtrace = "0.5"
 
-[dependencies.embedded-spi]
-version = "0.6"
-default-features = false 
-
 [dev-dependencies]                     # for examples
 cortex-m = "0.6.7"
 cortex-m-rt = "0.6.13"