Merged ECP memory usage optimizations

ChangeLog

diff --git a/ChangeLog b/ChangeLog
index 3078c58..030d720 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -19,6 +19,7 @@
    * More constant-time checks in the RSA module
    * Split off curves from ecp.c into ecp_curves.c
    * Curves are now stored fully in ROM
+   * Memory usage optimizations in ECP module
 
 Bugfix
    * Fixed bug in mpi_set_bit() on platforms where t_uint is wider than int