lz4: fix function name in error message
fix lz4 support reporting in --version

* In #223, lzo compression support dropped and add lz4 compression support.
Merge pull request #224 from cosmo0920/fix-support-reporting-lz4

fix lz4 support reporting in --version

Patch by Hiroshi Hatake. Thanks!!!
mruby: follow weight number may be int32 change
Use "Iu" for size_t on Windows
Make buildable on no atomic 64bit operation environment such as PowerPC

It makes buildable but it's not recommended to use on the environment.
You will see many warning messages on build.
Add output type accessor

It's not needed for normal Groonga C API users. Language bindings
developers may want to use it.
Add document of grn_content_type

TODO:
  * Update file list
  * Check build error (I don't build it yet. Sorry.)
test: follow LZO -> LZ4 change
Add "uncompressed_" prefix for readability
Support sort for compressed column

It is implemented by copied existing grn_obj_get_value_() based sort
implementation. Because I don't have idea to implement without
reducing performance for the current sort implementation. :<

The current implementation isn't changed except function and type
names. So performance isn't changed.
Use GRN_TRUEP() to handle value as boolean
Handle binary operation for vector as an error

Groonga crashes without this check.
Add in_values() function

    in_values(column, value1, value2, value3, ...)

equals to

    ((column == value1) OR (column == value2) OR (column == value3) OR ...)

It will be fast than == and OR combinations.

TODO:

  * Document me.
test in_values: add tests for value type (e.g. ShortText) column
Fix unexpected DB compatibility broken

Old DB doesn't have token filters information.
load: support updating existing record by _id key
Increase the max number of function arguments

8 -> 128
Close accessor for the same value
Fix a bug that "!XXX" may return inverted result

It may be happened on big endian environment.