[age restriction] progress 10/n

More work towards support for extensions:
- Prepared statements and DB-plugin-functions for setting and retrieving
  configurations from the database added.
- primitive "registry" of extensions for age restrictions and peer2peer
  (stub)
- TALER_Extensions now with FP for parsing, setting and converting a
  configuration.
- /management/extensions handler now verifies signature of the (opaque)
  json object for all extensions.
- /management/extensions handler calls the FP in the corrensponding
  TALER_Extension for parsing and setting the configuration of a
  particular extension

More work towards age restriction:
- TALER_Extensions interfaces for config-parser, -setter and converter
  implemented for age restriction
- DB event handler now retrieves config from database, parses it and
  sets it (the age mask) in the global extension.
- load_age_mask now loads age mask from the global extension (and not
  from the config file)
- add age_restricted_denoms to /keys response

1 files changed, 3 insertions, 2 deletions

diff --git a/src/util/extension_age_restriction.c b/src/util/extension_age_restriction.c
index c0efd7cd..42a58b2e 100644
--- a/src/util/extension_age_restriction.c
+++ b/src/util/extension_age_restriction.c
@@ -23,7 +23,6 @@
 #include "taler_extensions.h"
 #include "stdint.h"
 
-
 /**
  *
  * @param cfg Handle to the GNUNET configuration
@@ -137,12 +136,14 @@ TALER_parse_age_group_string (char *groups,
 
 
 /**
+ * Encodes the age mask into a string, like "8:10:12:14:16:18:21"
+ *
  * @param mask Age mask
  * @return String representation of the age mask, allocated by GNUNET_malloc.
  *         Can be used as value in the TALER config.
  */
 char *
-TALER_age_mask_to_string (struct TALER_AgeMask *m)
+TALER_age_mask_to_string (const struct TALER_AgeMask *m)
 {
   uint32_t mask = m->mask;
   unsigned int n = 0;