lumiera_error_set() now takes an optional extra string which can be used
to pass context relevant data along. This string gets copied into the
error state so one can easily create it by the tmpbuf_snprintf() facility.
Also a lot of places which define errors get fixed according to this.
Acquiring mutexes is now wraped in a easy to use MUTEX_SECTION macro.
This scheme will be extended for chained lock propagation soon.
Notes:
* NoBug resourcemanagement is now part of the lower layer,
RESOURCE_ENTER/RESOUCE_LEAVE are maintained automatically
* one must still call RESOURCE_ANNOUNCE/RESOURCE_FORGET, because we want
to maintain high level information about resources.
* MUTEX_SECTIONS must not be left with any kind of jump
lumiera_free() is for now just a static inline wraper around free()
Later this makes it easier to hook in some resource managing functions
or a Garbage Collector in.
Replaced all current uses of free()
* add 'backend' for backend global initialization/destruction
and common functions.
* WIP: 'file' acts as interface to named files, provides posix
filehandles with and acquire/release function pair.
* 'filehandle' manages posix filehandles internally, refcounted.
* WIP: 'filehandlecache' keeps unused filehandles in a MRU cache
* WIP: test for filehandle management
* improved filedescriptor test
We have 'File' which associates a name with a file and will be used to
offer an interface for the application.
Posix 'Filehandles' which are managed in a 'Filehandlecache' to utilize
a limited number of fd's at optimum.
Internally we use 'Filedescriptor's which manage files, mapping and all
kinds of metadata. Filedescriptors weak referenced by a registry and freed
when the last user vanishes.
