Bug: SLP1 `\` and `^`

[akprasad]

Code:

import aksharamukha.transliterate as a
print(a.process("SLP1", "Devanagari", "a\\ a^"))

Expected: अ॒ अ॑
Actual: अ\ अ^

Details on SLP1 accent: https://www.sanskritlibrary.org/pub/SLP1LiesAppendixB.pdf section B.3.3