Various fixes for VLMs (#3063)

* fix to not use batch feature indexing

* more vlm fixes

* use AutoModelForImageTextToText

* add example yaml and need num2words for chat template

* improve handling of adding image tokens to conversation

* add lfm2-vl support

* update the lfm readme

* fix markdown and add rtol for loss checks

* feat: add smolvlm2 processing strat

* fix: check for causal-conv1d in lfm models

* feat: add docs for lfm2

* feat: add new models and tips to docs

* feat: add smolvlm2 docs and remove extra dep

* chore: update docs

* feat: add video instructions

* chore: cleanup

* chore: comments

* fix: typo

* feat: add usage stats

* chore: refactor

---------

Co-authored-by: NanoCode012 <nano@axolotl.ai>

examples/LiquidAI/lfm2-350m-fft.yaml

@@ -0,0 +1,49 @@
+base_model: LiquidAI/LFM2-350M
+
+chunked_cross_entropy: true
+
+eot_tokens:
+  - "<|im_end|>"
+datasets:
+  - path: mlabonne/FineTome-100k
+    type: chat_template
+    split: train[:20%]
+    field_messages: conversations
+    message_field_role: from
+    message_field_content: value
+dataset_prepared_path: last_run_prepared
+val_set_size: 0.05
+output_dir: ./outputs/out
+
+sequence_len: 4096
+sample_packing: true
+
+
+wandb_project:
+wandb_entity:
+wandb_watch:
+wandb_name:
+wandb_log_model:
+
+gradient_accumulation_steps: 2
+micro_batch_size: 4
+num_epochs: 1
+optimizer: adamw_torch_fused
+lr_scheduler: cosine
+learning_rate: 5e-5
+
+bf16: true
+tf32: true
+
+gradient_checkpointing: false
+resume_from_checkpoint:
+logging_steps: 1
+flash_attention: true
+
+warmup_ratio: 0.1
+evals_per_epoch: 2
+saves_per_epoch: 1
+
+weight_decay: 0.0
+
+# save_first_step: true  # uncomment this to validate checkpoint saving works with your config