er-13 has changed the type of notify_subscribers counter to int32_t
from uint16_t which breaks builds of WITH_COAP=3 or 7.

This patch changes the 03 and 07 engine to int32_t.

An alternate fix would be to switch out the type in erbuim.h based on
WITH_COAP.

Or, maybe better, would be to drop old COAP versions.
Added support for <input type='hidden'>.

Hidden form fields are aded to the page attribute buffer like text form fields so there's no need for special treatment in formsubmit(). However they are not added as widgets to the window so there's no user interaction.
Merge pull request #159 from oliverschmidt/master

Added support for <input type='hidden'>.
Restored Contiki compatibility with non-C99 compilers.

(and compilers without non-standard extensions like void pointer arithmetic)
Merge pull request #161 from oliverschmidt/master

Restored Contiki compatibility with non-C99 compilers.
Added support for strncasecmp() which is now used in resolv.c.
Merge pull request #162 from oliverschmidt/master

Added support for strncasecmp() which is now used in resolv.c.
Some coding style nomalization.
Merge pull request #163 from oliverschmidt/master

Some coding style nomalization.
Merge pull request #154 from malvira/erbium-build-fixes-er3-7

Fix er 3 and 7 buids in latest erbuim (subscribers counter has changed type)
Some more changes improving code style conformance and code size.
Merge pull request #165 from oliverschmidt/master

Some more changes improving code style conformance and code size.
Reduced code size.

Combined recent changes from darconeous...
- Refactor to decrease minimum code footprint.
- Added `RESOLV_CONF_SUPPORTS_RECORD_EXPIRATION`.
...with a few additional changes to reduce code size.
Merge pull request #166 from oliverschmidt/master

Reduced code size.
Added configurations of the new resolver.
Merge pull request #167 from oliverschmidt/master

Added configurations of the new resolver.
core/net/resolv: Fix for SDCC.
core/net/resolv: Fix for resolving CNAME records.
core/net/resolv: Misc. updates and cleanups.
Merge pull request #168 from darconeous/pull-requests/core-net-resolv-misc

Miscellaneous small DNS resolver updates and fixes