add codes for data reading and PCA

Dependencies:   mpu9250_i2c Eigen

Revision:
2:145ba8262ed2
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Eigen.lib	Wed Nov 20 01:37:11 2019 +0000
@@ -0,0 +1,1 @@
+https://os.mbed.com/users/ykuroda/code/Eigen/#13a5d365ba16