Improved batch verification for Lelantus one-of-many proofs

[AaronFeickert]

Improves batch verification for Lelantus one-of-many proofs by reducing to a single multiscalar multiplication operation. Adds additional sanity checks for the prover and verifier routines. Removes redundant code while retaining backwards compatibility.

Review requested.

[lgtm-com]

This pull request introduces 1 alert and fixes 2 when merging 8f3591c into 677b54c - view on LGTM.com

new alerts:

• 1 for Unused static function

fixed alerts:

• 2 for Unused static function

[lgtm-com]

This pull request introduces 1 alert and fixes 2 when merging 00168ca into 677b54c - view on LGTM.com

new alerts:

• 1 for Comparison result is always the same

fixed alerts:

• 2 for Unused static function

[lgtm-com]

This pull request fixes 2 alerts when merging df2f52b into 677b54c - view on LGTM.com

fixed alerts:

• 2 for Unused static function

[lgtm-com]

This pull request fixes 2 alerts when merging 14287d8 into e2c8db6 - view on LGTM.com

fixed alerts:

• 2 for Unused static function

[lgtm-com]

This pull request fixes 3 alerts when merging 695012a into e3f929c - view on LGTM.com

fixed alerts:

• 3 for Unused static function

[lgtm-com]

This pull request introduces 2 alerts when merging e21f215 into 8192c5f - view on LGTM.com

new alerts:

• 2 for Unused static function

[lgtm-com]

This pull request introduces 2 alerts when merging 0ebcdc6 into c4918fd - view on LGTM.com

new alerts:

• 2 for Unused static function

[lgtm-com]

This pull request fixes 4 alerts when merging 02d1381 into 7960de9 - view on LGTM.com

fixed alerts:

• 4 for Unused static function

[lgtm-com]

This pull request fixes 3 alerts when merging 381a73b into b2eba12 - view on LGTM.com

fixed alerts:

• 3 for Unused static function

[levonpetrosyan93]

Here are the performance numbers
N = 65536 n = 16 m = 4 M = 1
Verify time New 907 ms
Verify time Old 899 ms
N = 65536 n = 16 m = 4 M = 5
Verify time New 945 ms
Verify time Old 941 ms
N = 65536 n = 16 m = 4 M = 10
Verify time New 1036 ms
Verify time Old 1027 ms
N = 65536 n = 16 m = 4 M = 50
Verify time New 1407 ms
Verify time Old 1501 ms
N = 65536 n = 16 m = 4 M = 100
Verify time New 1914 ms
Verify time Old 2071 ms
N = 65536 n = 16 m = 4 M = 500
Verify time New 6113 ms
Verify time Old 8149 ms
N = 65536 n = 16 m = 4 M = 1000
Verify time New 11347 ms
Verify time Old 12348 ms