Minor version header

[aghster]

Hi @ifedoroff,

first of all many thanks for your very useful libraries compound-file-js and msg-parser-js!

I just came across an Outlook msg file for which compound-file-js throwed an error. I found out that this was due to the minor version entry of the header of that file being 0x21, whereas compound-file-js apparently only accepts 0x3E:

compound-file-js/src/Header.ts

Line 28 in e676fd8

public static readonly MINOR_VERSION_3 = [0x3E, 0x00];

compound-file-js/src/Header.ts

Lines 64 to 65 in ac35746

	if(!equal(Header.MINOR_VERSION_3, dataView.subView(Header.FLAG_POSITION.MINOR_VERSION, Header.FLAG_POSITION.MINOR_VERSION +2).getData()))
	throw new Error();

As it seems the minor version "SHOULD be set to 0x003E". However, conversely, this means that it is not mandatory. Interestingly, according to https://en.wikipedia.org/wiki/Compound_File_Binary_Format#CFBF_Header_format some reference implementation uses 33 (=0x21) as the value of the minor version (this seems to be taken from here).

Unfortunately, the thrown error cannot be easily circumvented - at least I didn't find out how. This is why I suggest that, in addition to 0x3E, compound-file-js should accept other values, or at least 0x21, for the minor version header. What do you think?