CIOStream:
* Use flag based system instead (common flags are aliased; uses std::ios_base::openmode).
* 'ReadString' now writes into a string buffer (reference) that needs to be passed in by programmer (avoids copy).
* 'm_nSize' is now synced with any write operations.
CSigCache:
* Fixed bug causing crash when 'DecompressBlob' failed (results were never checked).
* Light formatting improvements.
Field 'm_bInitialized' should be set prior to calling this, this field was named differently and its use case was inverted, forgot to reflect changes in assert.
* Add '-nosmap' command line parameter to disable signature caching.
* Invalidate the cache map after initialization.
* Add const qualifiers where possible.
This implementation was done to calculate buffer CRC on the go, as that was what the VPK file system uses for the file crc's. But it later turned out to be unnecessary, and was never reverted.
* Fixed bug where the system still added entries after we are initialized (file has already been written to the disk).
* Moved loading logic to CSigCache class.
* Dedicated and Host/Client now have their own cache files.
