Openpecha

Fix
* **metadata:** Add seperate metadata classes for pecha types ([`904f926`](https://github.com/OpenPecha-dev/openpecha-toolkit/commit/904f9264c2e895e1ff9f9e85abb15109f70177e7))
* **core:** Replace source id with initial id ([`ca083be`](https://github.com/OpenPecha-dev/openpecha-toolkit/commit/ca083be3f723ed3d9015b92e145c6830def16a3b))
* **core:** Add source and diplomatic id generator ([`24549dd`](https://github.com/OpenPecha-dev/openpecha-toolkit/commit/24549dd5c710caa506c022f999ab74a197564fed))

Fix
* **core:** Add copyright and license in metadata ([`1db55da`](https://github.com/OpenPecha-dev/openpecha-toolkit/commit/1db55dad74631ee98b26d8d3127c598ec310c82e))
* **core-metadata:** Typos ([`d1b44f0`](https://github.com/OpenPecha-dev/openpecha-toolkit/commit/d1b44f03a88b2275b3122bb3505b52141f59c964))
* **core:** Move metadata model into metadata.py module ([`9f6f1a3`](https://github.com/OpenPecha-dev/openpecha-toolkit/commit/9f6f1a3c51a8b3f0b85f482393f36f4bf6d0b204))

Documentation
* **metadata:** Add copyright and license to metadata ([`b15ab56`](https://github.com/OpenPecha-dev/openpecha-toolkit/commit/b15ab56e5acdcb055887c5ad315a8bc5473d3f07))

Fix
* **serializer:** Apply index updated ([`be9a831`](https://github.com/OpenPecha-dev/openpecha-toolkit/commit/be9a8311939a5b9cdfc0947e35af3b5767cddcda))
* **serializer:** Vol id variables are renamed as base_id and vol keyword in span are changed to base ([`1d6898d`](https://github.com/OpenPecha-dev/openpecha-toolkit/commit/1d6898d9be7376963f865ec3da56547862a906c9))

Fix
* **corpus:** Create corpus directory ([`7ea0b5f`](https://github.com/OpenPecha-dev/openpecha-toolkit/commit/7ea0b5fc168d68b1a0e4e37ad0b8faeb0f3cd9e1))

Fix
* **core:** Remove prints ([`0cacb3d`](https://github.com/OpenPecha-dev/openpecha-toolkit/commit/0cacb3d267538150ece4161f05ee84ddfb62f3a0))
* **core:** Add metadata attr to OpenPecha class ([`8c5cb98`](https://github.com/OpenPecha-dev/openpecha-toolkit/commit/8c5cb98ab0068ae0e95ece3826ecfd72b42c4e8d))
* **core:** Set base text metadata ([`5f34da2`](https://github.com/OpenPecha-dev/openpecha-toolkit/commit/5f34da2851bb8693cc0015f58985d5e58fc42b83))

Fix
* **corpus:** Refactor to download tokenized corpus ([`b68bef0`](https://github.com/OpenPecha-dev/openpecha-toolkit/commit/b68bef00d0f7168484aded5f989032714d33526e))
* **corpus:** Lazy downloading corpus catalog csv file ([`cf24270`](https://github.com/OpenPecha-dev/openpecha-toolkit/commit/cf24270df4bbf993158cc2e0f17400138a5110e3))