spectrum_cass.xml: Added 34 working items. (#13245)

Also improved metadata with information from Spectrum Computing.

New working software list additions (spectrum_cass.xml)
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Channel 1 - Spectrum Music Club - Issue 5 (Jan. 1991) [Planeta Sinclair, Steven Brown]
Channel 1 - Spectrum Music Club - Double Issue 6 + 7 (Sept. 1991) [Planeta Sinclair, Steven Brown]
Computer Form Pools Predictions [Planeta Sinclair, Steven Brown]
Libreria de Software Spectrum № 6 (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 6 (covertape, alt) [Spectrum Computing]
Libreria de Software Spectrum № 7 (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 7 (covertape, alt) [Spectrum Computing]
Libreria de Software Spectrum № 8 (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 9 (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 9 (covertape, alt) [Spectrum Computing]
Libreria de Software Spectrum № 10 (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 10 (covertape, alt) [Spectrum Computing]
Libreria de Software Spectrum № 11 (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 12 (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 12 (covertape, alt) [Spectrum Computing]
Libreria de Software Spectrum № 13 (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 14 - Spy Chip (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 14 - Spy Chip (covertape, alt) [Spectrum Computing]
Libreria de Software Spectrum № 15 - Invasion (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 16 - Carr-2001 (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 17 - Xirius (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 18 - Zortron (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 18 - Zortron (covertape, alt) [Spectrum Computing]
Libreria de Software Spectrum № 19 - Argon (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 19 - Argon (covertape, alt) [Spectrum Computing]
Libreria de Software Spectrum № 20 - Night (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 21 - Voyager (covertape) [Spectrum Computing]
Libreria de Software Spectrum № 22 - Blue Lands (covertape) [Spectrum Computing]
Light Force (Zafi Chip) [Spectrum Computing]
Lode Runner (48K) [Spectrum Computing]
Misiles [Spectrum Computing]
Sample Editor [Planeta Sinclair, Steven Brown]
Silent 'e' & /y/ Rules [Planeta Sinclair, Steven Brown]
VTX 711 Prestel & Terminal Software [Planeta Sinclair, Steven Brown]