Params refactor, simplified (#2300)

* always c++

* Create C++ params class

* get works

* tests hang now

* passes tests

* cleanup string formatting

* handle interrupt in blocking read

* fix memory leak

* remove unused constructor

* Use delete_db_value directly

* Rename put -> write_db_value

* filename cleanup

* no semicolons in cython

* Update common/SConscript

Co-authored-by: Adeeb Shihadeh <adeebshihadeh@gmail.com>

* add std::string version of delete_db_value

* This is handled

* cleanup encoding

* Add clear method to clear all

* add persistent params

* fix android build

* Should be called clear_all

* only import params when needed

* set params path on manager import

* recusrively create directories

* Fix function order

* cleanup mkdirp

Co-authored-by: Adeeb Shihadeh <adeebshihadeh@gmail.com>
Co-authored-by: Comma Device <device@comma.ai>
old-commit-hash: 2e182e5c57

common/params_pyx_setup.py

@@ -0,0 +1,21 @@
+import os
+from distutils.core import Extension, setup
+from Cython.Build import cythonize
+from common.cython_hacks import BuildExtWithoutPlatformSuffix
+from common.basedir import BASEDIR
+
+sourcefiles = ['params_pyx.pyx']
+extra_compile_args = ["-std=c++11"]
+
+setup(name='common',
+      cmdclass={'build_ext': BuildExtWithoutPlatformSuffix},
+      ext_modules=cythonize(
+        Extension(
+          "params_pyx",
+          language="c++",
+          sources=sourcefiles,
+          include_dirs=[BASEDIR, os.path.join(BASEDIR, 'selfdrive')],
+          extra_compile_args=extra_compile_args
+        )
+      )
+)