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/mbedtls/ChangeLog.d/move-mbedtls-ecc-psa-helpers.txt

@@ -0,0 +1,3 @@
+Changes
+    * Moved declaration of functions mbedtls_ecc_group_to_psa and
+      mbedtls_ecc_group_of_psa from psa/crypto_extra.h to mbedtls/psa_util.h