Support for PC platform (#12)

* improvements for cross-platform compiling

* moved tactility-core to libs/

* splitup improvements

* remove git/gitmodules from freertos

* better platformbetter platform checks

* added build scripts

* delete mbedtls

* re-add mbedtls

* fixes and improvements

* added pc build

* simplify build scripts

* revert build scrpit

* updated builds

* fix for pc

* fix for pc

* fix for build

libs/freertos-kernel/portable/ThirdParty/GCC/RP2040/README.md

@@ -0,0 +1,30 @@
+## Overview
+
+This directory provides a FreeRTOS-Kernel port that can be used with the Raspberry Pi Pico SDK. It supports:
+
+ * Simple CMake INTERFACE libraries, to provide the FreeRTOS-Kernel and also the individual allocator types, without copying code into the user's project.
+ * Running the FreeRTOS-Kernel and tasks on either core 0 or core 1
+ * Use of SDK synchronization primitives (such as mutexes, semaphores, queues from pico_sync) between FreeRTOS tasks and code executing on the other core, or in IRQ handlers.
+
+Note that a FreeRTOS SMP version of this port is also available in the FreeRTOS-Kernel smp branch, which additionally supports utilizing both RP2040 CPU cores for FreeRTOS tasks simultaneously.
+
+## Using this port
+
+Copy [FreeRTOS-Kernel-import.cmake](FreeRTOS-Kernel-import.cmake) into your project, and
+add:
+
+```cmake
+import(FreeRTOS_Kernel_import.cmake)
+```
+
+below the usual import of `pico_sdk_import.cmake`
+
+This will find the FreeRTOS kernel if it is a direct sub-module of your project, or if you provide the `FREERTOS_KERNEL_PATH` variable in your environment or via `-DFREERTOS_KERNEL_PATH=/path/to/FreeRTOS-Kernel` on the CMake command line.
+
+## Advanced Configuration
+
+Some additional `config` options are defined [here](include/rp2040_config.h) which control some low level implementation details.
+
+## Known Limitations
+
+- Tickless idle has not currently been tested, and is likely non-functional