Updated the flocra interpreter code

[sairamgeethanath]

Refer to commit 4b0dac9

1. Now compatible with the latest pypulseq interpreter 1.4.2: format of the pulseq file has changed since 1.3.2
2. Can get rid of the external/pypulseq folder; now only install the pip package - refer requirements.txt
3. Unlocks a cleaner implementation by reading only the seq object, the file write can be for book-keeping; needs modifying sequences to directly pass seq object; in progress
4. Checked until the output of Marcos spectrometer (Redpitaya 122.8) for all sequences in the sequence library

[sairamgeethanath]

@Anais-A - Could you please review this PR?